JP4216033B2 - Variable gain amplifier - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a variable gain amplifying device having a gain control function.In placeIt is related.
[0002]
[Prior art]
The first-stage amplifier of a receiving device in a wireless system typified by a mobile phone needs to have low noise and high gain characteristics when receiving a weak signal, and when receiving a large signal, Low distortion and low gain characteristics are required.
[0003]
In particular, in recent mobile communications, the electric field strength at the time of reception varies greatly depending on the distance between the base station and the mobile station, so that a large dynamic range is required for the receiving device, and as a result, the first stage of the receiving device. The amplifier is required to have a gain control function.
[0004]
FIG. 21 shows a circuit configuration of a main part of a mobile phone terminal in which a conventional variable gain amplifying device having such a gain control function is used (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3). . The mobile phone terminal shown in FIG. 21 is used in digital wireless communication using a modulation method such as QPSK.
[0005]
In FIG. 21, the mobile phone terminal includes an antenna 1, an antenna duplexer 2, a transmission circuit unit 3, a variable gain amplifying device 4, a mixer 7, a filter 8, mixers 9, 10, a local oscillator 11, and a phase shifter 12. The The variable gain amplifying device 4, the mixer 7, the filter 8, the mixers 9, 10, the local oscillator 11 and the phase shifter 12 constitute a receiving circuit unit. The mixer 9, the mixer 10, the local oscillator 11, and the phase shifter 12 constitute an orthogonal demodulator.
[0006]
The antenna 1 transmits a transmission signal as a transmission wave and receives a reception wave as a reception signal. The antenna duplexer 2 is a circuit that guides the transmission signal output from the transmission circuit unit 3 to the antenna 1 and guides the received wave received by the antenna 1 to the variable gain amplifier 4. The variable gain amplifying device 4 is a circuit that amplifies a received signal as a first-stage amplifier of a receiving circuit unit. The mixer 7 is a circuit that converts an amplified received signal into an intermediate frequency signal by synthesizing a signal input from an oscillator (not shown) with the received signal amplified by the variable gain amplifier 4. The filter 8 is a circuit that reduces unnecessary frequency components in the signal converted into the intermediate frequency signal. The mixer 10 is a circuit that demodulates the baseband I signal by combining the signal output from the filter 8 and the signal input from the local oscillator 11. The mixer 9 is a circuit that demodulates the baseband Q signal by combining the signal output from the filter 8 and the signal whose phase is changed by 90 degrees by the phase shifter 12. The phase shifter 12 is a circuit that changes the phase of the signal oscillated by the local oscillator 11 by 90 degrees.
[0007]
The variable gain amplifying apparatus 4 includes an amplifier 5 and a switching element 6.
[0008]
Next, the operation of such a conventional mobile phone terminal will be described.
[0009]
A received signal received by the antenna 1 is amplified by the variable gain amplifying device 4 via the antenna duplexer 2. The mixer 7 converts the reception signal amplified by the variable gain amplifier 4 into an intermediate frequency signal, and the filter 8 reduces unnecessary frequency components of the converted intermediate frequency signal.
[0010]
On the other hand, the signal from the local oscillator 11 is output to the mixer 10 and the phase shifter 12. The mixer 10 demodulates the baseband I signal by combining the output signal from the filter 8 and the signal input from the local oscillator 11.
[0011]
The phase shifter 12 outputs a signal obtained by changing the phase of the signal from the local oscillator 11 by 90 degrees to the mixer 9, and the mixer 9 combines the output signal from the filter 8 and the signal from the phase shifter 12. By doing so, the baseband Q signal is demodulated.
[0012]
The demodulated baseband I signal and baseband Q signal are input to a baseband unit (not shown) and restored to digital audio data in the baseband unit.
[0013]
By the way, when the mobile phone terminal is present in the vicinity of the base station, the received signal received by the antenna 1 becomes large. In such a case, a large received signal is also input to the variable gain amplifier 4. In such a case, the variable gain amplifying apparatus 4 is controlled so that the supply of the power supply voltage for operating the amplifier 5 is stopped and the switching element 6 is turned on. Therefore, a large received signal input from the antenna duplexer 2 passes through the switching element 6 and is output to the mixer 7 without being amplified by the amplifier 5. That is, the variable gain amplifying device 4 operates with a low gain. Thus, the variable gain amplifying apparatus 4 operates in the low gain mode when the received signal is large.
[0014]
On the other hand, when the mobile phone terminal exists at a location far from the base station, the received signal received by the antenna 1 becomes weak. In such a case, a weak received signal is also input to the variable gain amplifier 4. In such a case, the variable gain amplifying device 4 is controlled so that a power supply voltage for operating the amplifier 5 is supplied, and the switching element 6 is turned off. Therefore, the weak received signal input from the antenna duplexer 2 is amplified by the amplifier 5 without passing through the switching element 6 and output to the mixer 7. That is, the variable gain amplifying apparatus 4 operates with a high gain. Thus, the variable gain amplifying apparatus 4 operates in the high gain mode when the received signal is weak.
[0015]
As described above, the variable gain amplifying apparatus 4 operates in the low gain mode when the received signal is large, and operates in the high gain mode when the received signal is weak, and thus has a wide dynamic range. I can do it.
[0016]
[Patent Document 1]
JP-A-8-18348
[Patent Document 2]
Japanese Patent Laid-Open No. 10-173453
[Patent Document 3]
Japanese Patent Laid-Open No. 11-261479
[0017]
[Problems to be solved by the invention]
However, the inventors have found that when the variable gain amplifying device 4 operates in the low gain mode, the amount of change in the phase of the received signal when passing through the variable gain amplifying device 4 and the variable gain amplifying device 4 operates in the high gain mode. In this case, it was found that the amount of change in the phase of the received signal when passing through the variable gain amplifying device 4 is different.
[0018]
Therefore, when the variable gain amplifying device 4 is switched from the low gain mode to the high gain mode, or when the variable gain amplifying device 4 is switched from the high gain mode to the low gain mode, the phase of the signal output from the variable gain amplifying device 4 is discontinuous. The quadrature demodulator composed of the mixer 9, the mixer 10, the local oscillator 11, and the phase shifter 12 cannot be synchronized. Therefore, until the synchronization is established, the quadrature demodulator cannot normally demodulate the baseband I signal and the baseband Q signal.
[0019]
The above will be described in more detail. First, a case where the quadrature demodulator normally demodulates the baseband I signal and the baseband Q signal will be described.
[0020]
Assume that the input signal to the quadrature modulator is expressed by the following equation (1).
[0021]
[Expression 1]
S (t) = I (t) · cosωt + Q (t) sinωt
However, I (t) is a digital signal that takes +1 or -1.
Q (t) is a digital signal that takes +1 or -1.
In this case, since the local oscillator 11 is synchronized with the input signal S (t) to the quadrature modulator, the local oscillator 11 outputs a signal oscillating at cos ωt to the mixer 10. Therefore, the mixer 10 combines the signal output from the local oscillator 11 and the input signal to the quadrature demodulator, so that the output signal from the mixer 10 is expressed by the following equation (2).
[0022]
[Expression 2]
S (t) · cosωt = I (t) · (1/2) · (cos2ωt + 1)
+ Q (t) ・ (1/2) ・ sin2ωt
By passing this output signal through a low-pass filter not shown in FIG. 21, the baseband I signal represented by the following equation 3 is demodulated.
[0023]
[Equation 3]
(1/2) ・ I (t)
On the other hand, the output signal cosωt from the local oscillator 11 is input to the phase shifter 12, and the phase shifter 12 outputs a sinωt signal to the mixer 9 by changing the phase by 90 degrees. The mixer 9 combines the signal output from the phase shifter 12 and the input signal to the quadrature demodulator, and the output signal from the mixer 9 is expressed by the following equation (4).
[0024]
[Expression 4]
S (t) · sinωt = I (t) · (1/2) · sin2ωt
+ Q (t) · (1/2) · (1-cos2ωt)
By passing this output signal through a low-pass filter not shown in FIG. 21, the baseband Q signal represented by the following equation 5 is demodulated.
[0025]
[Equation 5]
(1/2) ・ Q (t)
As described above, when the input signal S (t) to the quadrature demodulator and the signal oscillated by the local oscillator 11 are synchronized, the baseband I signal and the baseband Q signal are normally output by the quadrature demodulator. It can be demodulated.
[0026]
  FIG. 22 (a) shows examples of demodulated values of the baseband I signal and the baseband Q signal expressed by Equations 3 and 5, respectively. That is, in FIG.(A)Then, I (t) and Q (t) take the same value, and show a case where +1, -1, +1. In addition, when I (t) and Q (t) are given in FIG. 22B, the demodulated baseband I signal is plotted on the horizontal axis and the demodulated baseband Q signal is plotted on the vertical axis. The figure is shown. The set of the baseband I signal and the baseband Q signal shown in (a) of FIG. 22 is plotted at the points in the first quadrant and the third quadrant in (b) of FIG. When these points are connected by a straight line, the straight line forms an angle of 45 degrees with respect to the horizontal axis.
[0027]
Here, it is assumed that the variable gain amplifying apparatus 4 is switched from the low gain mode to the high gain mode or from the high gain mode to the low gain mode because the magnitude of the received signal received by the antenna 1 has changed. In this case, as described above, when the variable gain amplifying device 4 operates in the low gain mode, the amount of change in the phase of the received signal when it passes through the variable gain amplifying device 4, and the variable gain amplifying device 4 in the high gain mode. When operating, the amount of change in the phase of the received signal when passing through the variable gain amplifying device 4 is different. Therefore, the phase of the input signal S (t) to the quadrature demodulator changes by φ.
[0028]
Therefore, the input signal S (t) to the quadrature modulator is expressed by the following equation (6).
[0029]
[Formula 6]
S (t) = I (t) · cos (ωt + φ) + Q (t) sin (ωt + φ)
However, I (t) is a digital signal that takes +1 or -1.
Q (t) is a digital signal that takes +1 or -1.
In this case, the local oscillator 11 outputs a signal oscillating at cos ωt to the mixer 10. Therefore, the mixer 10 combines the signal output from the local oscillator 11 and the input signal to the quadrature demodulator, whereby the output signal from the mixer 10 is expressed by the following equation (7).
[0030]
[Expression 7]
S (t) · cosωt = I (t) · (1/2) · (cosφ + cos2ωt)
+ Q (t) · (1/2) · (−sinφ + sin2ωt)
By passing this output signal through a low-pass filter not shown in FIG. 21, the baseband I signal expressed by the following equation 8 is demodulated.
[0031]
[Equation 8]
(1/2) · (I (t) · cosφ−Q (t) · sinφ)
On the other hand, the output signal cosωt from the local oscillator 11 is input to the phase shifter 12, and the phase shifter 12 outputs a sinωt signal to the mixer 9 by changing the phase by 90 degrees. The mixer 9 combines the signal output from the phase shifter 12 and the input signal to the quadrature demodulator, and the output signal from the mixer 9 is expressed by the following equation (9).
[0032]
[Equation 9]
S (t) · sinωt = I (t) · (1/2) · (sinφ + sin2ωt)
+ Q (t) · (1/2) · (cosφ−cos2ωt)
By passing this output signal through a low-pass filter not shown in FIG. 21, the baseband Q signal expressed by the following equation 10 is demodulated.
[0033]
[Expression 10]
(1/2) · (I (t) · sinφ + Q (t) · cosφ)
As described above, when the phase of the input signal S (t) to the quadrature modulator is changed by switching the mode of the variable gain amplifying device 4, the demodulated baseband I signal and baseband Q signal are changed. Changes as shown in FIG. That is, (a) of FIG. 22 changes as shown in (a) of FIG. 23, and (b) of FIG. 22 changes as shown in (b) of FIG. That is, the set of the baseband I signal and the baseband Q signal shown in FIG. 23A is plotted at the points in the first quadrant and the third quadrant in FIG. When these points are connected by a straight line, the straight line changes to an angle larger than 45 degrees with respect to the horizontal axis.
[0034]
Thus, if the set of values of the baseband I signal and the baseband Q signal demodulated in (a) of FIG. 22 is (1, 1), the mode of the variable gain amplifying device 4 is switched. This value set may also move towards the second quadrant. In some cases, it may also move toward the third quadrant.
[0035]
Thus, the baseband I signal and the baseband Q signal are not changed until the local oscillator 11 is synchronized with the input signal to the quadrature demodulator after the mode of the variable gain amplifying apparatus 4 is switched. Therefore, the audio digital signal cannot be restored normally, which may cause a break in the received voice of the mobile phone terminal or mixing of noise.
[0036]
That is, when the gain of the variable gain amplifying device is switched, there is a problem that the phase of the signal output from the variable gain amplifying device changes discontinuously.
[0037]
  In consideration of the above problems, the present invention provides a variable gain amplifying device capable of sufficiently minimizing the discontinuous change in the phase output from the variable gain amplifying device even when the gain of the variable gain amplifying device is switched.PlaceIt is intended to provide.
[0038]
[Means for Solving the Problems]
  In order to solve the above-described problem, the first present invention includes an amplifier,
  A first switching element connected in parallel with the amplifier;
  A phase shifter connected in series to the first switching element,
  SaidPhase shiftThe vesselA capacitor and a resistor having one end connected to the capacitor and the other end groundedA multi-stage circuit composed of n basic unit circuits (n is a natural number of 2 or more) composed of
  Basic unit circuits from the first stage to the n-th stage constituting the multi-stage circuit are as follows:A first stage basic unit circuit is connected to the first switching element, and (i-1) stage basic unit circuit capacitor (i is a natural number from 2 to n) and i stage basic unit circuit capacitor. ButConnected in seriesAnd
The resistance value of the resistor of the i-th basic unit circuit of the phase shifter is set to a times the resistance value of the resistor of the (i-1) -th basic unit circuit (a is a predetermined real number greater than 1). And the capacitance value of the capacitor of the i-th basic unit circuit is set to 1 / a times the capacitance value of the capacitor of the (i-1) -th basic unit circuit, whereby the input impedance of the phase shifter is set. | Z | The output impedance of the phase shifter is a with respect to (Z is a predetermined complex number). ⁿ ・ | Z | Set to
The input impedance of the amplifier is the input impedance of the phase shifter | Z | And the output impedance of the amplifier is a ⁿ ・ | Z | Is set to
  The first switching element is turned on when the level of the input signal or the output signal is higher than a predetermined level, and the level of the input signal or the output signal is equal to the predetermined level or the predetermined level If it is smaller, it is turned off.
  The amplifier does not operate when the first switching element is in an on state, and operates when the first switching element is in an off state;
  Of the phase when the input signal passes through the amplifier.AdvanceAnd the phase when the input signal passes through the first switching element and the phase shifter.AdvanceThis is a variable gain amplifying device having the same amount.
[0040]
  According to a second aspect of the present invention, the first switching element includes a second switching element and a third switching element.
  One of the second switching elements is connected to an input of the amplifier;
  The other of the second switching elements is connected to one of the phase shifters,
  The other of the phase shifters is connected to one of the third switching elements,
  The other of the third switching elements is the variable gain amplifier according to the first aspect of the present invention connected to the output of the amplifier.The
[0053]
DETAILED DESCRIPTION OF THE INVENTION
  Embodiments of the present invention are described below.And embodiments of the invention related to the present invention,This will be described with reference to the drawings.
[0054]
  (First embodiment)
  First,Of the invention related to the present inventionA first embodiment will be described.
[0055]
FIG. 1 shows a variable gain amplifying apparatus 18 of the present embodiment. The variable gain amplifying device 18 is used, for example, as the variable gain amplifying device 4 of the mobile phone terminal of FIG.
[0056]
The variable gain amplifying device 18 includes an amplifier 13, a switching element 14, and a phase shifter 15.
[0057]
The amplifier 13 has its input connected to the input terminal 16, and its output is output to the output terminal 17. In addition, one of the switching elements 14 is connected to the input of the amplifier 13, and the other is connected to one of the phase shifters 15. The other side of the phase shifter 15 is connected to the output of the amplifier 13. The input terminal 16 is a terminal to which the reception signal output from the preceding stage such as the antenna duplexer 2 is input in FIG. 21, and the output terminal 17 receives the signal amplified by the variable gain amplifier 18 in FIG. This is a terminal for outputting to a subsequent stage such as the mixer 7.
[0058]
Thus, the variable gain amplifying apparatus 18 according to the present embodiment has a configuration in which the switching element 14 is connected in parallel to the amplifier 13 and the phase shifter 15 is connected in series to the switching element 14. Have.
[0059]
Next, the operation of this embodiment will be described.
[0060]
The variable gain amplifying apparatus 18 of the present embodiment operates by being controlled according to a control circuit (not shown). The control circuit controls the operation of the variable gain amplifying apparatus 18 according to the level of the received signal received by the antenna 1.
[0061]
That is, the switching element 14 is controlled to be turned on when the level of the input signal is higher than a predetermined level, and to be turned off when the input signal is at the predetermined level or lower than the predetermined level.
[0062]
Further, the amplifier 13 is controlled so as not to operate when the switching element 14 is in an on state, and to operate when the switching element 14 is in an off state. In this control, for example, when the amplifier 13 is operated, the power supply voltage for operating the amplifier 13 is supplied, and when the operation of the amplifier 13 is stopped, the power supply voltage for operating the amplifier 13 is supplied. Done by stopping.
[0063]
  Therefore, when the level of the received signal is larger than the predetermined level, the variable gain amplifying device18Operates in low gain mode. That is, since the switching element is turned on and the amplifier 13 stops operating, the received signal is output from the input terminal 16 through the switching element 14 and the phase shifter 15 from the output terminal 17.
[0064]
On the other hand, when the level of the received signal is the predetermined level or lower than the predetermined level, the variable gain amplifying apparatus 18 operates in the high gain mode. That is, since the switching element is turned off and the amplifier 13 operates, the received signal is amplified by the amplifier 13 from the input terminal 16 and output from the output terminal 17.
[0065]
  The phase shifter 15 receives the received signal as an amplifier.13The phase shifter 15 so that the amount of change in the phase of the received signal when it passes through and the amount of change in the phase of the received signal when the received signal passes through the switching element 14 and the phase shifter 15 are substantially equal. The phase of the received signal input to is changed.
[0066]
Therefore, even if the variable gain amplifying device 18 is switched from the high gain mode to the low gain mode or the low gain mode is switched to the high gain mode by changing the signal level of the received signal, the output The phase of the signal output from the terminal 17 does not change discontinuously.
[0067]
That is, even when the mode of the variable gain amplifying apparatus 18 is switched, the phase of the input signal input to the quadrature demodulator in FIG. 21 does not change discontinuously. It is possible to prevent voice interruptions and noise. Therefore, by using the variable gain amplifying apparatus 18 of the present embodiment as a first-stage amplifier of a receiving device in a wireless system typified by a mobile phone, it is possible to provide a mobile phone terminal or the like with high received voice quality.
[0068]
In the present embodiment, the switching element 14 is connected to the input of the amplifier 13 and the phase shifter 15 is connected to the output of the amplifier 13. However, the present invention is not limited to this.
[0069]
FIG. 2 shows a variable gain amplifying apparatus 19 having a configuration different from that shown in FIG. In the variable gain amplifying device 19, the switching element 14 is connected to the output of the amplifier 13, and the phase shifter 15 is connected to the input of the amplifier 13. The variable gain amplifying device 19 is obtained by switching the insertion positions of the switching element 14 and the phase shifter 15 of the variable gain amplifying device 18 of FIG. That is, one of the phase shifters 15 is connected to the input of the amplifier 13, the other of the phase shifters 15 is connected to one of the switching elements 14, and the other of the switching elements 14 is the output of the amplifier 13. It is connected to the. Even if the variable gain amplifying device 19 is used, the same effect as described above can be obtained.
[0070]
FIG. 3 shows a variable gain amplifying apparatus 21 having a configuration different from that shown in FIG. Unlike the variable gain amplifying apparatus 18 of FIG. 1, the variable gain amplifying apparatus 21 includes two switching elements. In other words, in the variable gain amplifying apparatus 21, one of the switching elements 14 is connected to the input of the amplifier 13, the other of the switching elements 14 is connected to the phase shifter 15, and the other of the phase shifters 15 is Are connected to one of the switching elements 20, and the other of the switching elements 20 is connected to the output of the amplifier 13.
[0071]
The switching elements 14 and 20 are turned on when the level of the reception signal input from the input terminal 16 is higher than a predetermined level, and the reception signal input from the input terminal 16 is at a predetermined level or predetermined. When it is smaller than the level, it is turned off. In addition, the amplifier 13 is not operated when the switching elements 14 and 20 are turned on by controlling the power supply voltage for operating the amplifier 13 in the same manner as in the above embodiment, and the switching elements 14 and 20 are not operated. Works when is off.
[0072]
The phase shifter 15 is configured such that the amount of change in the phase of the received signal when the received signal input from the input terminal 16 passes through the amplifier 13 and the received signal input from the input terminal 16 are the switching element 14 and the phase shifter. 15. The phase of the reception signal input to the phase shifter 15 is changed so that the amount of change in the phase of the reception signal when passing through the switching element 20 is substantially equal.
[0073]
Further, in the variable gain amplifying apparatus 18 of FIG. 1, when the reception signal input to the input terminal 16 is at a predetermined level or a reception signal that is lower than the predetermined level is input, the switching element 14 is turned off. However, the other of the phase shifters 15 remains connected to the output of the amplifier 13. Therefore, since the phase shifter 15 is connected to the output of the amplifier 13, the characteristics of the amplifier 13 are deteriorated somewhat.
[0074]
Similarly, in the variable gain amplifying apparatus 19 of FIG. 2, when the reception signal input to the input terminal 16 is at a predetermined level or a reception signal smaller than the predetermined level is input, the switching element 14 is turned off. However, one of the phase shifters 15 remains connected to the input of the amplifier 13. Therefore, since the phase shifter 15 is connected to the input of the amplifier 13, the characteristics of the amplifier 13 are somewhat deteriorated.
[0075]
  In contrast, in FIG.Variable gainAmplification equipment21Then, when a reception signal that is at a predetermined level or lower than the predetermined level is input to the input terminal 16, both the switching element 14 and the switching element 20 are turned off. Insulated from the input and output. Therefore, in the variable gain amplifying apparatus 21 of FIG. 3, in addition to the effect of the present embodiment, it is possible to obtain the effect that the specific deterioration of the amplifier 13 by the phase shifter 15 can be prevented.
[0076]
FIG. 25A shows a variable gain amplifying apparatus 61 having a configuration different from that shown in FIG. In the variable gain amplifying device 61, unlike the variable gain amplifying device 18 of FIG. 1, a phase shifter 15 a is connected in series with the amplifier 13. That is, in the variable gain amplifying device 61, one of the switching elements 14 is connected to the input of the amplifier 13, and the other of the switching elements 14 is connected to one of the phase shifters 15a. The other is connected to the output of the amplifier 13. The phase shifter 15a is different from the phase shifter 15 of the variable gain amplifying apparatus 18 of FIG. That is, the phase shifter 15a is configured such that the amount of change in the phase of the received signal when the received signal passes through the amplifier 13 and the phase shifter 15a, and the amount of change in the phase of the received signal when the received signal passes through the switching element 14. And the phase of the received signal input to the phase shifter 15a is changed so as to be substantially equal.
[0077]
Further, the positions of the phase shifter 15a and the amplifier 13 of the variable gain amplifying apparatus 61 may be switched. FIG. 25B shows such a variable gain amplifying device 62. In the variable gain amplifying device 62, one of the phase shifters 15 a is connected to the input of the amplifier 13, and the other of the phase shifters 15 a is connected to one of the switching elements 14. The output of the amplifier 13 is connected to the other of the switching elements 14. Thus, even if the positions of the phase shifter 15a and the amplifier 13 are interchanged, the same effect as in the present embodiment can be obtained. As shown in FIGS. 25A and 25B, the amplifier 13 and the phase shifter 15a can be connected in series.
[0078]
  (Second Embodiment)
  next,Of the invention related to the present inventionA second embodiment will be described.
[0079]
FIG. 4 shows a variable gain amplifying apparatus 24 of the present embodiment. The variable gain amplifying device 24 is used, for example, as the variable gain amplifying device 4 of the mobile phone terminal of FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
[0080]
The variable gain amplifier 24 includes an amplifier 13, a switching element 14, a phase shifter 15, a switching element 20, a feedback circuit 22, and a switching element 23.
[0081]
  The amplifier 13 has its input connected to the input terminal 16, and its output is output to the output terminal 17. In addition, one of the switching elements 14 is connected to the input of the amplifier 13, and the other is connected to one of the phase shifters 15. The other of the phase shifters 15 is connected to one of the switching elements 20, and the other of the switching elements 20 is connected to the output of the amplifier 13. One of the switching elements 23 is connected to the output of the amplifier 13, the other of the switching elements 23 is connected to one of the feedback circuits 22, and the other of the feedback circuits 22 is the amplifier.13Connected to the input.
[0082]
Next, the operation of this embodiment will be described.
[0083]
  The variable gain amplifying device 24 of the present embodiment operates by being controlled according to a control circuit (not shown) as in the first embodiment. And this control circuit is a variable gain amplifier according to the level of the received signal received by the antenna 1.24To control the operation.
[0084]
That is, the switching elements 14 and 20 are controlled to be turned on when the level of the input signal is higher than a predetermined level, and to be turned off when the input signal is at the predetermined level or lower than the predetermined level. .
[0085]
Further, the amplifier 13 is controlled so as not to operate when the switching element 14 is in an on state, and to operate when the switching element 14 is in an off state. In this control, for example, when the amplifier 13 is operated, the power supply voltage for operating the amplifier 13 is supplied, and when the operation of the amplifier 13 is stopped, the power supply voltage for operating the amplifier 13 is supplied. Done by stopping. Further, when the switching elements 14 and 20 are in the on state, the switching element 23 is in the off state, and when the switching elements 14 and 20 are in the off state, the switching element 23 is in the on state.
[0086]
Therefore, when the level of the received signal is larger than the predetermined level, the variable gain amplifying device 24 operates in the low gain mode. That is, the switching elements 14 and 20 are turned on, the amplifier 13 stops operating, and the switching element 23 is turned off, so that the received signal is input from the input terminal 16 to the switching element 14 and the phase shifter 15. And the output from the output terminal 17 via the switching element 20.
[0087]
  On the other hand, if the level of the received signal is a predetermined level or smaller than the predetermined level, the variable gain amplifying device24Operates in high gain mode. That is, the switching elements 14 and 20 are turned off, the amplifier 13 is operated, and the switching element 23 is turned on, so that the received signal is amplified by the amplifier 13 from the input terminal 16 and is output from the output terminal 17. In addition to being output, a part of the output signal from the amplifier 13 is negatively fed to the input of the amplifier 13 via the switching element 23 and the feedback circuit 22.
[0088]
The phase shifter 15 changes the phase change amount of the received signal when the received signal passes through the amplifier 13 and the phase of the received signal when the received signal passes through the switching element 14, the phase shifter 15, and the switching element 20. The phase of the received signal input to the phase shifter 15 is changed so that the amount of change is substantially equal.
[0089]
Therefore, even if the variable gain amplifier 24 is switched from the high gain mode to the low gain mode or the low gain mode is switched to the high gain mode by changing the signal level of the received signal, the output The phase of the signal output from the terminal 17 does not change discontinuously.
[0090]
  That is, variable gainamplificationEven when the mode of the device 24 is switched, the phase of the input signal input to the quadrature demodulator in FIG. 21 does not change discontinuously. Can be prevented. Therefore, by using the variable gain amplifying apparatus 24 of the present embodiment as a first-stage amplifier of a receiving device in a wireless system typified by a mobile phone, it is possible to provide a mobile phone terminal or the like with high received voice quality.
[0091]
FIG. 5 shows a variable gain amplifier 25 in which the insertion positions of the switching element 23 and the feedback circuit 22 of the variable gain amplifier 24 of FIG. That is, in the variable gain amplifying apparatus 25, one of the switching elements 23 is connected to the input of the amplifier 13, the other of the switching elements 23 is connected to one of the feedback circuits 22, and the other of the feedback circuits 22 is the amplifier 13. Connected to the output. Even if such a variable gain amplifying device 25 is used, an effect equivalent to that of the present embodiment can be obtained.
[0092]
  (Third embodiment)
  next,Of the present inventionA third embodiment will be described.
[0093]
FIG. 6 shows a circuit diagram of the variable gain amplifying apparatus 30 of the present embodiment.
[0094]
In the variable gain amplifying apparatus 30 shown in FIG. 6, the input terminal P1 is connected to one of the DC side input side capacitors 131, and the other side of the input side capacitor 131 is one side of the switching element 121 and the base of the transistor 101. It is connected to the. A bias power supply circuit 107 is connected to the base of the transistor 101, the emitter of the transistor 101 is grounded via an inductor 103 that widens the input dynamic range, and the collector of the transistor 101 is connected to the emitter of the transistor 102. . The base of the transistor 102 is connected to the bias power supply circuit 108 and to the grounded bypass capacitor 106. The collector of the transistor 102 is connected to one of the output-side capacitor 133 for DC cutoff and one of the negative feedback-side capacitor 105 for DC cutoff, and the collector of the transistor 102 further includes a choke coil 132 for high-frequency cutoff. To the amplifier power supply terminal Vcc. The other of the output side capacitors 133 is connected to the output terminal P2.
[0095]
The other side of the negative feedback side capacitor 105 is connected to one of the switching elements 123 and one of the switching elements 122. The other of the switching element 123 is connected to one of the resistors 104 for applying negative feedback, and the other of the resistors 104 is connected to the base of the transistor 101.
[0096]
The other side of the switching element 122 is connected to one of the capacitors 116, and the other side of the capacitor 116 is connected to one of the grounded resistor 113 and capacitor 115. The other side of the capacitor 115 is connected to one of the grounded resistor 112 and capacitor 114. The other of the capacitor 114 is connected to the other of the grounded resistor 111 and the switching element 121.
[0097]
  The switching element power supply terminal 31 is connected to the control terminals of the switching element 121 and the switching element 122. Further, the switching element power supply terminal 31 is connected to one side of the inverter 124, and the other side of the inverter 124 is the control of the switching element 123.For your useConnected to the terminal.
[0098]
The variable gain amplifying apparatus 30 of the present embodiment corresponds to the variable gain amplifying apparatus 24 of FIG. 4 of the second embodiment.
[0099]
That is, the input terminal P1 corresponds to the input terminal 16 in FIG. 4, the terminal P2 corresponds to the output terminal 17 in FIG. 4, and the resistor 104 corresponds to the feedback circuit 22 in FIG. The inverter 124 and the switching element 123 correspond to the switching element 23 in FIG. 4, and the transistors 101 and 102, the capacitor 106, the inductor 103, and the bias power supply circuits 107 and 108 correspond to the amplifier 13 in FIG. Yes. The capacitors 114, 115, and 116 and the resistors 111, 112, and 113 correspond to the phase shifter 15 in FIG. 4, and the switching element 121 corresponds to the switching element 14 in FIG. The element 122 corresponds to the switching element 20 of FIG.
[0100]
The switching element power supply terminal 31 is a terminal that supplies a power supply voltage for switching the on state and the off state of the switching elements 121, 122, and 123.
[0101]
The bias power supply circuit 107 is a circuit for supplying a bias voltage to the base of the transistor 101, and the bias power supply circuit 108 is a circuit for supplying a bias voltage to the base of the transistor 102, and is controlled by a control circuit (not shown). This is a circuit capable of stopping or starting the supply of the operating voltage.
[0102]
The amplifier power supply terminal Vcc is a terminal for supplying an operating voltage to the transistor 102 and the transistor 101.
[0103]
  Switching element power supply terminal31Is for switching the ON state and the OFF state of the switching elements 121, 122, 123 by supplying or stopping the control power supply voltage to the control terminals of the switching elements 121, 122, 123 by a control circuit (not shown). Terminal.
[0104]
Note that the terminals such as the input terminal P1 and the output terminal P2 in this embodiment include a terminal such as a pad electrode and a node that is a connection point between elements in the wiring.
[0105]
The resistors 111, 112, 113, etc. are made of polysilicon, and the capacitors 114, 115, 116, etc. are made of MOS capacitors. Note that the capacitors 114, 115, and 116 may be configured with MIM capacitors.
[0106]
Next, the operation of this embodiment will be described.
[0107]
When the variable gain amplifying apparatus 30 is used in the high gain mode, the received signal is amplified by elements such as the transistor 101 and the transistor 102, and these elements, that is, the elements corresponding to the amplifier 13 in FIG. It is assumed that the phase of the reception signal output from the output terminal P2 advances from the phase of the reception signal input to the terminal P1. Further, it is assumed that the input impedance to the base of the transistor 101 is smaller than the output impedance of the collector of the transistor 102.
[0108]
  First, variable gain amplificationapparatusThe case where 30 operates in the high gain mode will be described.
[0109]
  When the level of the received signal input from the input terminal P1 is equal to or lower than the predetermined level, the high gain mode is set. That is, when a control circuit (not shown) detects that the level of the received signal is lower than a predetermined level, a voltage that turns off the switching elements 122 and 121 as a control voltage supplied to the switching element power supply terminal 31. (For example, a voltage of 0V) is supplied. In addition, the control circuit (not shown)Power supplyA voltage for operating the transistors 101 and 102 is supplied from the circuits 107 and 108. Accordingly, the transistor 101 and the transistor 102 are in an operating state.
[0110]
At this time, the reception signal input from the input terminal P 1 passes through the input side capacitor 131 and is input to the base of the transistor 101. In addition, the input reception signal does not flow into the capacitor 114 because the switching element 121 is in an off state. A bias voltage is supplied to the base of the transistor 101 by a bias power supply circuit 107, and a bias voltage is supplied to the base of the transistor 102 by a bias power supply circuit 108. The received signal input to the base of the transistor 101 is amplified by the transistor 101 and the transistor 102 and output from the collector of the transistor 102.
[0111]
A part of the signal output from the collector of the transistor 102 passes through the output-side capacitor 133 and is output from the output terminal P2 to a subsequent stage such as the mixer 7. The remainder of the signal output from the collector of the transistor 102 passes through the negative feedback side capacitor 105. The signal that has passed through the negative feedback side capacitor 105 passes through the switching element 123, is adjusted to a predetermined signal level by the resistor 104, and is input to the base of the transistor 101 again. Further, the signal that has passed through the negative feedback side capacitor 105 does not flow into the capacitor 116 because the switching element 122 is in the OFF state.
[0112]
Thus, in the high gain mode, the received signal input from the input terminal P1 is amplified by the transistors 101 and 102 while receiving negative feedback, and is output from the output terminal P2 to the subsequent stage.
[0113]
At this time, the phase of the reception signal output from the output terminal P2 is higher than the phase of the reception signal input from the input terminal P1, and the input impedance | Zi (high) | It is assumed that the output impedance | Zo (high) | However, both Zi (high) and Zo (high) are complex numbers.
[0114]
  Next, variable gain amplificationapparatusA case where 30 operates in the low gain mode will be described.
[0115]
When the level of the received signal input from the input terminal P1 is higher than a predetermined level, the low gain mode is set. That is, when a control circuit (not shown) detects that the level of the received signal is greater than a predetermined level, the control circuit enters a low gain mode in order to prevent the transistors 101 and 102 from being saturated.
[0116]
That is, when a control circuit (not shown) detects that the level of the received signal is higher than a predetermined level, the voltage that turns on the switching elements 122 and 121 as the control voltage supplied to the switching element power supply terminal 31. (For example, a voltage of 3V) is supplied. Further, a control circuit (not shown) stops supplying the voltage at which the transistors 101 and 102 operate from the amplifier power supply terminal Vcc. Accordingly, the transistors 101 and 102 are stopped.
[0117]
At this time, the received signal input from the input terminal P1 passes through the input-side capacitor 131, passes through the switching element 121, and passes through the circuit portion composed of the capacitors 114, 115, 116 and the resistors 111, 112, 113. pass. As described above, this circuit portion functions as the phase shifter 15 in FIG. In this circuit portion, the phase of the received signal input from the input terminal P1 is adjusted so as to advance.
[0118]
Specifically, the relationship between the resistance value of the resistor 111, the resistance value of the resistor 112, and the resistance value of the resistor 113 is 1: a: a²Are in a relationship. Further, the relationship between the capacitance value of the capacitor 114, the capacitance value of the capacitor 115, and the capacitance value of the capacitor 116 is a²: A: 1 relationship. However, a is adjusted to a predetermined value larger than 1.
[0119]
In the circuit portion functioning as the phase shifter 15 in FIG. 4, basic unit circuits composed of resistors and capacitors are coupled in three stages. The circuit portion functioning as the phase shifter 15 in FIG. 4 also serves as an impedance converter.
[0120]
Assuming that the input impedance of the circuit composed of the resistor 111 and the capacitor 114, which is the basic unit circuit in the first stage, is Z1, the output impedance of this circuit can be expressed as a | Z1 | using the predetermined number a. . However, Z1 is a complex number. Therefore, since the input impedance of the circuit composed of the resistor 112 and the capacitor 115, which is the second-stage basic unit circuit, is a | Z1 |, the output impedance of this circuit is expressed as²| Z1 |. Accordingly, the input impedance of the circuit composed of the resistor 113 and the capacitor 116, which is the basic unit circuit of the third stage, is a²Since | Z1 |, the output impedance of this circuit is a^Three| Z1 |. In this way, the impedance of the output of the basic unit circuit at the front stage and the impedance of the input at the rear stage are relatively close to each other, and the loss between stages is reduced. Furthermore, the frequency characteristics of the passing phase are also relatively equal.
[0121]
On the other hand, as described above, in the high gain mode, the input impedance of the base of the transistor 101 is | Zi (high) |, the output impedance of the collector of the transistor 102 is | Zo (high) |, and | Zi (High) | is smaller than the output impedance | Zo (high) | of the collector of the transistor 102.
[0122]
Therefore, the above a is a value that satisfies the following expression 11.
[0123]
## EQU11 ##
| Zo (high) | / | Zi (high) | = a^Three
Further, by setting Z1 to an impedance relatively close to Zi (high), the output impedances of the high gain mode and the low gain mode are also close to each other. In this case, since the passing phase of the circuit portion functioning as the phase shifter 15 in FIG. 4 is uniquely determined, the value close to the passing phase in the high gain mode can be obtained by increasing or decreasing the number of stages of the basic unit circuit composed of resistors and capacitors. To do. In the case where the circuit portion functioning as the phase shifter 15 in FIG. 4 is composed of n-stage (n is an integer of 1 or more) basic unit circuits, the above a is a value that satisfies the following formula 12. Good.
[0124]
[Expression 12]
| Zo (high) | / | Zi (high) | = aⁿ
Therefore, by passing through this circuit portion, the reception signal is output from the output terminal P2 with the phase advance amount substantially the same as the advance amount of the passing phase in the high gain mode.
[0125]
  That is, the signal that has passed through this circuit portion passes through the switching element 122. Switching element123Since the signal is in the off state, this signal does not flow to the resistor 104 side. Therefore, the signal passing through the switching element 122 passes through the negative feedback side capacitor 105 and is output from the output terminal P2 via the output side capacitor 133.
[0126]
As described above, since the phase of the signal passing through the portion corresponding to the phase shifter 15 in FIG. 4 is adjusted, even when the mode is switched from the high gain mode to the low gain mode, the signal is output from the output terminal P2. The discontinuous change in the phase of the signal to be generated can be made sufficiently small.
[0127]
In the variable gain amplifying apparatus 30 of the present embodiment, as shown in FIG. 26, a resistor 2641 is inserted between the switching element 122 and the ground, a resistor 2642 is inserted between the switching element 123 and the ground, and a capacitor 2643. May be inserted between the base of the transistor 101 and the resistor 104. As a result, at least one end of the switching elements 121, 122, and 123 becomes zero potential, so that the switching element is reliably turned on / off, and insertion loss at the time of on is improved.
[0128]
Further, instead of the resistors 2641 and 2642, an inductor and a quarter wavelength line may be used.
[0129]
Although the variable gain amplifying apparatus 30 of the present embodiment has been described as an unbalanced circuit, it can also be realized as a balanced circuit.
[0130]
That is, FIG. 7 shows a variable gain amplifying apparatus 32 that implements the variable gain amplifying apparatus 30 of the present embodiment as a balanced circuit.
[0131]
  The input terminal P1 in FIG. 6 is the input terminal P1a in FIG.as well as6, the input side capacitor 131 in FIG. 6 is replaced with the input side capacitors 131a and 131b in FIG. 7, and the switching element 121 in FIG. 6 is replaced with the switching elements 121a and 121b in FIG. The transistor 101 is replaced with transistors 101a and 101b in FIG. 7, the transistor 102 in FIG. 6 is replaced with transistors 102a and 102b in FIG. 7, and the inductor 103 in FIG. 6 is replaced with inductors 103a and 103b in FIG. 7 is replaced with resistors 104a and 104b in FIG. 7, the output side capacitor 133 in FIG. 6 is replaced with output side capacitors 133a and 133b in FIG. 7, and the choke coil 132 in FIG. 6 is replaced with the choke coil 132a in FIG. , 132b 6 is replaced with negative feedback side capacitors 105a and 105b in FIG. 7, and the inverter 124 and switching element 123 in FIG. 6 are the inverters 124a and 124b and switching element in FIG. 7, respectively. The switching element 122 in FIG. 6 is replaced with the switching elements 122a and 122b in FIG. 7, and the capacitors 114, 115, and 116 in FIG. 6 are respectively replaced with the capacitors 114a and 114b, the capacitors 115a and 115a in FIG. 115b and capacitors 116a and 116b, the output terminal P2 in FIG.FIG.Then, the output terminals P2a and P2b are replaced. Since other than that is the same as that of the variable gain amplifier 30 of this Embodiment, description is abbreviate | omitted.
[0132]
Note that the variable gain amplifying apparatus 32 according to the present embodiment may also be configured such that at least one end of the switching elements 121, 122, 123a, and 123b has a zero potential, similarly to the variable gain amplifying apparatus 30 according to the present embodiment. Thereby, the switching element is reliably turned on / off, and the insertion loss at the time of on is improved.
[0133]
As described above, the variable gain amplifying apparatus 30 of the present embodiment can be realized by a balanced circuit such as the variable gain amplifying apparatus 32, for example.
[0134]
6, when used in the high gain mode, the received signal passes through the circuit portion corresponding to the amplifier 13 in FIG. 4, so that the received signal input to the input terminal P <b> 1. The case where the phase of the received signal output from the output terminal P2 is advanced from the phase and the input impedance to the base of the transistor 101 is smaller than the output impedance of the collector of the transistor 102 has been described, but corresponds to the amplifier 13 of FIG. When the characteristics of the circuit part to be performed are other than that, it is necessary to change the circuit part corresponding to the phase shifter 15 of FIG.
[0135]
First, FIG. 8 shows a circuit diagram of a variable gain amplifying apparatus 33 in which a circuit portion corresponding to such a phase shifter 15 is changed. In the variable gain amplifying apparatus 33, the passing phase of the received signal in the high gain mode advances, and the input impedance of the portion corresponding to the amplifier 13 is larger than the output impedance of that portion.
[0136]
In the variable gain amplifying device 33, the part corresponding to the phase shifter 15 of FIG. 4 is connected to one of the switching elements 121 with one of the capacitors 314 and the other of the capacitors 314 with a grounded resistor 311. At the same time, it is connected to one of the capacitors 315. A grounded resistor 312 is connected to the other side of the capacitor 315 and is connected to one side of the capacitor 316. A grounded resistor 313 is connected to the other side of the capacitor 316 and also connected to one side of the switching element 122.
[0137]
In the variable gain amplifying device 33, the circuit portion functioning as the phase shifter 15 in FIG. 4 adjusts the phase in the same manner as in the third embodiment.
[0138]
That is, the relationship between the resistance value of the resistor 311, the resistance value of the resistor 312, and the resistance value of the resistor 313 is 1: a: a²Are in a relationship. Further, the capacitance value of the capacitor 314 and the relationship between the capacitance value of the capacitor 315 and the capacitance value of the capacitor 316 are represented by a²: A: 1 relationship. However, a is adjusted to a predetermined value smaller than 1. That is, a is designed in advance so as to have the same phase advance amount as the phase advance amount of the reception signal output from the output terminal P2 with respect to the phase of the reception signal input from the input terminal P1 in the high gain mode. Value. Such a value can be determined in the same manner as described above.
[0139]
Therefore, by passing through this circuit portion, a signal having a phase advance amount substantially the same as the advance amount of the passing phase in the high gain mode is output from the output terminal P2.
[0140]
As described above, even if the passing phase of the reception signal in the high gain mode is advanced and the input impedance of the portion corresponding to the amplifier 13 is larger than the output impedance of the portion, the high gain mode is changed to the low gain mode. It is possible to sufficiently reduce the discontinuous change in the phase of the signal output from the output terminal P2 when switching to or from the low gain mode to the high gain mode.
[0141]
Note that the variable gain amplifying apparatus 33 according to the present embodiment may also be configured such that at least one end of the switching elements 121, 122, and 123 has a zero potential, similarly to the variable gain amplifying apparatus 30 according to the present embodiment. Thereby, the switching element is reliably turned on / off, and the insertion loss at the time of on is improved.
[0142]
Note that the variable gain amplifying apparatus 33 of the present embodiment can also be configured by a balanced circuit as described in the present embodiment.
[0143]
FIG. 9 shows a circuit diagram of another variable gain amplifying apparatus 34 in which the circuit portion corresponding to the phase shifter 15 is changed. The variable gain amplifying apparatus 34 in FIG. 9 is such that the reception signal passing phase in the high gain mode is delayed, and the input impedance of the portion corresponding to the amplifier 13 is smaller than the output impedance of that portion.
[0144]
  That is, in the portion corresponding to the phase shifter 15 in FIG. 4, one of the resistors 414 is connected to one of the switching elements 121, the grounded capacitor 411 is connected to one of the resistors 414, and the other of the resistors 414 is connected. Is connected to one end of resistor 415ThisIn addition, a grounded capacitor 412 is connected. A grounded capacitor 413 is connected to the other end of the resistor 415, and the other end of the resistor 415 is connected to one end of the resistor 416. In addition to the resistor 416PersonOne of the switching elements 122 is connected.
[0145]
The circuit portion functioning as the phase shifter 15 in FIG. 4 adjusts the phase as in the present embodiment.
[0146]
That is, the relationship between the resistance value of the resistor 414, the resistance value of the resistor 415, and the resistance value of the resistor 416 is 1: a: a²Are in a relationship. Further, the relationship between the capacitance value of the capacitor 411 and the capacitance value of the capacitor 412 and the capacitance value of the capacitor 413 is:²: A: 1 relationship. However, a is adjusted to a predetermined value smaller than 1. That is, a is designed in advance so as to have the same phase delay amount as the phase delay amount of the reception signal output from the output terminal P2 with respect to the phase of the reception signal input from the input terminal P1 in the high gain mode. Value. Such a value can be determined in the same manner as described above.
[0147]
Accordingly, by passing through this circuit portion, a signal having a phase delay amount substantially the same as the delay amount of the passing phase in the high gain mode is output from the output terminal P2.
[0148]
As described above, even when the passing phase of the received signal in the high gain mode is delayed and the input impedance of the portion corresponding to the amplifier 13 is smaller than the output impedance of the portion, the high gain mode is changed to the low gain mode. It is possible to sufficiently reduce the discontinuous change in the phase of the signal output from the output terminal P2 when switching to or from the low gain mode to the high gain mode.
[0149]
Note that the variable gain amplifying apparatus 34 of the present embodiment may have a configuration in which at least one end of the switching elements 121, 122, and 123 has a zero potential, similarly to the variable gain amplifying apparatus 30 of the present embodiment. Thereby, the switching element is reliably turned on / off, and the insertion loss at the time of on is improved.
[0150]
Note that the variable gain amplifying apparatus 34 of the present embodiment can also be configured by a balanced circuit as described in the present embodiment.
[0151]
FIG. 10 shows a circuit diagram of another variable gain amplifying apparatus 35 in which the circuit portion corresponding to the phase shifter 15 is changed. The variable gain amplifying apparatus 35 of FIG. 10 has a delayed passage phase of the received signal in the high gain mode, and the input impedance of the portion corresponding to the amplifier 13 is larger than the output impedance of that portion.
[0152]
In the portion corresponding to the phase shifter 15 in FIG. 4, one of the resistors 514 is connected to one of the switching elements 121, and the grounded capacitor 511 is connected to the other of the resistors 514, and the other of the resistors 514 is connected to the other. Is connected to one end of the resistor 515. A grounded capacitor 512 is connected to the other end of the resistor 515, and the other end of the resistor 515 is connected to one of the resistors 516. A grounded capacitor 513 is connected to the other end of the resistor 516, and one of the switching elements 122 is connected to the other end of the resistor 516.
[0153]
The circuit portion functioning as the phase shifter 15 in FIG. 4 adjusts the phase as in the present embodiment.
[0154]
That is, the relationship between the resistance value of the resistor 514, the resistance value of the resistor 515, and the resistance value of the resistor 516 is 1: a: a²Are in a relationship. Further, the relationship between the capacitance value of the capacitor 511, the capacitance value of the capacitor 512, and the capacitance value of the capacitor 513 is: a²: A: 1 relationship. However, a is adjusted to a predetermined value smaller than 1. That is, a is designed in advance so as to have the same phase delay amount as the phase delay amount of the reception signal output from the output terminal P2 with respect to the phase of the reception signal input from the input terminal P1 in the high gain mode. Value. Such a value can be determined in the same manner as described above.
[0155]
Accordingly, by passing through this circuit portion, a signal having a phase delay amount substantially the same as the delay amount of the passing phase in the high gain mode is output from the output terminal P2.
[0156]
As described above, even when the passing phase of the received signal in the high gain mode is delayed and the input impedance of the portion corresponding to the amplifier 13 is larger than the output impedance of the portion, the high gain mode is changed to the low gain mode. It is possible to sufficiently reduce the discontinuous change in the phase of the signal output from the output terminal P2 when switching to or from the low gain mode to the high gain mode.
[0157]
Note that the variable gain amplifying apparatus 35 of the present embodiment may have a configuration in which at least one end of the switching elements 121, 122, and 123 becomes 0 potential, similarly to the variable gain amplifying apparatus 30 of the present embodiment. Thereby, the switching element is reliably turned on / off, and the insertion loss at the time of on is improved.
[0158]
Note that the variable gain amplifying apparatus 35 can also be configured by a balanced circuit as described in the present embodiment.
[0159]
As the switching elements 121, 122, and 123, for example, an FET switch formed of gallium and arsenic, a triple well MOSFET switch, a silicon on insulator switch, or the like can be used.
[0160]
FIG. 11 schematically shows a cross-sectional configuration of the high-frequency switching element 50 used in the switching elements 121, 122, and 123. That is, the high frequency switching element is a triple well structure MOSFET switch.
[0161]
As shown in FIG. 11, the high frequency switching element 50 is formed in an element formation region defined by trench portions 608 and 609 selectively provided in a semiconductor substrate 601 made of, for example, P-type silicon.
[0162]
An n-type well 602 and a p-type well 603 surrounded by the n-type well 602 are formed in the element formation region of the semiconductor substrate 601.
[0163]
A drain layer 606 and a source layer 607 are formed in the p-type well 603 at a distance from each other, and a gate insulating film made of silicon oxide is formed in the region between the drain layer 606 and the source layer 607 on the p-type well 603. A gate electrode 605 made of polysilicon is formed via 604.
[0164]
  High frequency switching elementWhen 50 is the switching element 121 of FIG. 6, the drain layer 606 has the input side capacitor of FIG.131The source layer 607 is connected to an output node P20 that outputs a reception signal to the capacitor 114 and the resistor 111 shown in FIG.
[0165]
The gate electrode 605 is connected to a voltage control terminal P3 that receives supply of a control voltage from the switching element power supply terminal 31 via a resistor 611, and the n-type well 602 is connected to the voltage control terminal P3 via a resistor 610. .
[0166]
The semiconductor substrate 601 is grounded and the p-type well 603 is grounded via a resistor 612.
[0167]
In the high-frequency switching element 50 configured as described above, a reverse bias voltage is applied between the n-type well 602 and the p-type well 603, so that the pn connection formed by the interface between the n-type well 602 and the p-type well 603 is performed. Therefore, the n-type well 602 and the p-type well 603 are insulated from each other in a direction perpendicular to the substrate surface. Furthermore, since a reverse bias voltage is also applied between the semiconductor substrate 601 and the n-type well 602, a depletion layer is formed by a pn junction formed by the interface between the semiconductor substrate 601 and the n-type well 602, and the semiconductor substrate 601 and the n-type well 602 are formed. The wells 602 are isolated from each other.
[0168]
Therefore, when the high-frequency switching element 50 is in the ON state, the received signal input to the input node P10 is drain layer 606, the source layer 607, and the channel region formed between the drain layer 606 and the source layer 607 from the semiconductor substrate. The loss of the received signal caused by leaking to 601 can be reduced. As a result, the insertion loss due to the high frequency switching element 50 in the low gain mode can be reduced.
[0169]
Further, by using the triple well structure in this way, even when the high frequency switching element 50 is in the OFF state, the reception signal input to the input node P10 is generated via the drain layer 606 and is received to the semiconductor substrate 601. Leakage can be reduced. As a result, in the high gain mode, it is possible to reduce deterioration of noise characteristics due to part of the high frequency signal input to the input terminal P1 shown in FIG.
[0170]
  Instead of resistors 610, 611, 612SoAn inductor element may be used for each.
[0171]
  (Fourth embodiment)
  next,Of the invention related to the present inventionA fourth embodiment will be described.
[0172]
FIG. 12 shows a circuit diagram of the variable gain amplifying apparatus 36 of the fourth embodiment.
[0173]
The variable gain amplifying apparatus 36 of the present embodiment is configured such that a portion corresponding to the phase shifter 15 in FIG.
[0174]
The same parts as those in the third embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
[0175]
The variable gain amplifying apparatus 36 of the fourth embodiment is such that the reception signal passing phase is delayed in the high gain mode, and the input impedance of the portion corresponding to the amplifier 13 is smaller than the output impedance of that portion. is there.
[0176]
Further, the portion corresponding to the phase shifter 15 of FIG. 4 is different from the variable gain amplifying apparatus 33 of the third embodiment.
[0177]
That is, the portion corresponding to the phase shifter 15 in FIG. 4 is composed of strip lines 711, 712, and 713. One of the strip lines 711 is connected to one of the switching elements 121, the other of the strip lines 711 is connected to one of the strip lines 712, and the other of the strip lines 712 is connected to one of the strip lines 713. . The other end of the strip line 713 is connected to the switching element 122.
[0178]
The strip lines 711, 712, and 713 are each made of an aluminum wire. Note that the strip lines 711, 712, and 713 may be formed of copper wiring or gold wiring.
[0179]
Next, the operation of the present embodiment will be described with a focus on differences from the third embodiment.
[0180]
The circuit portion functioning as the phase shifter 15 in FIG. 4 adjusts the phase as in the third embodiment.
[0181]
That is, the relationship between the impedance value of the strip line 711, the impedance value of the strip line 712, and the impedance value of the strip line 713 is 1: a: a²Are in a relationship. However, a is adjusted to a predetermined value larger than 1. That is, a is designed in advance so as to have the same phase delay amount as the phase delay amount of the reception signal output from the output terminal P2 with respect to the phase of the reception signal input from the input terminal P1 in the high gain mode. Value.
[0182]
In the circuit portion that functions as the phase shifter 15 in FIG. 4, the basic unit circuit that is a strip line is coupled in three stages. The circuit portion functioning as the phase shifter 15 in FIG. 4 also serves as an impedance converter.
[0183]
  The impedance of the strip line 711, which is the basic unit circuit in the first stage, is Z1, and the transistor in the high gain mode is used.ThisZ1 is selected so that Z1 and | Zi (high) | are close to each other, assuming that the input impedance | Zi (high) |
[0184]
Further, when the impedance of the strip line 713 which is the third-stage basic unit circuit is Z3 and the output impedance of the collector of the transistor 102 is | Zo (high) |, Z3 and | Zo (high) | are close to each other. Choose Z3 so that
[0185]
Thus, Z1 is selected so that the input impedances in the high gain mode and the low gain mode are close to each other, and the output impedances in the high gain mode and the low gain mode are close to each other. Select Z3 as follows.
[0186]
Further, assuming that the impedance of the strip line 712, which is the second-stage basic unit circuit, is Z2, when Z1, Z2, and Z3 are usually real numbers and satisfy the following formula 13, the loss is small in a relatively wide frequency range. Become.
[0187]
[Formula 13]
Z2 = (Z1 · Z3)^1/2
Therefore, a may be selected so as to satisfy the following equation (14).
[0188]
[Expression 14]
Z2 = aZ1,
Z3 = a²Z1
Furthermore, the number of stages may be increased to widen the frequency range. For example, when the basic unit circuit in which the circuit portion functioning as the phase shifter 15 in FIG. 4 is a strip line is composed of four stages, Z1, Z2, Z3, and Z4 are the basic elements from the first stage to the fourth stage, respectively. When the impedance of the unit circuit is selected, if a is selected so as to satisfy the following equation 15, the loss is reduced in a wider frequency range than when the basic unit circuit has three stages.
[0189]
[Expression 15]
Z2 = aZ1,
Z3 = a²Z2
Z4 = a^ThreeZ3
In general, when the basic unit circuit portion is composed of n stages (n is an integer of 1 or more), a may be selected so as to satisfy the following equation (16).
[0190]
[Expression 16]
Z_{i + 1}= AⁱZ_i
However, i is an arbitrary integer from 1 to n-1.
[0191]
Similarly, the circuit portion functioning as the phase shifter 15 in FIG. 4 is constituted by one strip line whose line width continuously changes, and the basic unit circuit has three stages of impedance on the input side of the strip line. Z1 in this case, and the impedance on the output side of the stripline may be set to Z3 in the case where the basic unit circuit has a three-stage configuration.
[0192]
The phase can be adjusted by changing the total length of the strip line.
[0193]
Further, when the strip lines 711, 712, 713 are configured as microstrip lines, the impedance of the strip lines 711, 712, 713 is obtained as in the strip lines 711, 712, 713 as follows. I can do it.
[0194]
  That is, FIG. 24 shows a microstrip line 82 which is such a basic unit circuit. The microstrip line 82 is formed on the dielectric 81, and no dielectric is formed on the opposite side of the microstrip line 82 from the dielectric 81. The width of the microstrip line 82 is w, the height of the dielectric 81 is h, and the dielectric constant of the dielectric 81 is ε._rAnd In this case, when w / h is 1 or less,microImpedance Z of stripline 82₀Can be approximated as the following Expression 17.
[0195]
[Expression 17]
  If w / h is 1 or more,microThe impedance Z0 of the strip line 82 can be approximated as the following equation (18).
[0196]
[Formula 18]
However, εre is expressed by the following equation 19.
[0197]
[Equation 19]
Therefore, by adjusting the width w of the microstrip line 82, each basic unit circuit that satisfies, for example, Equation 16 can be obtained.
[0198]
Accordingly, by passing through this circuit portion, a signal having a phase delay amount substantially the same as the delay amount of the passing phase in the high gain mode is output from the output terminal P2.
[0199]
As described above, even when the passing phase of the received signal in the high gain mode is delayed and the input impedance of the portion corresponding to the amplifier 13 is smaller than the output impedance of the portion, the high gain mode is changed to the low gain mode. It is possible to sufficiently reduce the discontinuous change in the phase of the signal output from the output terminal P2 when switching to or from the low gain mode to the high gain mode.
[0200]
In the variable gain amplifying apparatus 36 of FIG. 12, the impedance is changed by using strip lines 711, 712, and 713 having different line widths, but the impedance is changed by using dielectrics having different relative dielectric constants or different thicknesses. It may be changed.
[0201]
Instead of the strip lines 711, 712, and 713, a line having a taper whose characteristic impedance changes from Z1 to Z4 may be used.
[0202]
Note that the variable gain amplifying apparatus 36 of the present embodiment may have a configuration in which at least one end of the switching elements 121, 122, and 123 becomes 0 potential, similarly to the variable gain amplifying apparatus 30 of the third embodiment. Thereby, the switching element is reliably turned on / off, and the insertion loss at the time of on is improved.
[0203]
Note that the variable gain amplifying apparatus 36 can also be constituted by a balanced circuit as described in the third embodiment.
[0204]
Further, when the input impedance of the portion corresponding to the amplifier 13 is larger than the output impedance of the portion and the passing phase of the received signal is delayed, the circuit portion corresponding to the phase shifter 15 in FIG. 4 is changed as follows. Then, the same effect as this embodiment can be obtained.
[0205]
That is, the variable gain amplifying device 37 of FIG. 13 has a delayed passage phase of the received signal in the high gain mode, and the input impedance of the portion corresponding to the amplifier 13 is larger than the output impedance of that portion.
[0206]
A portion corresponding to the phase shifter 15 in FIG. 4 is composed of strip lines 811, 812, 813. One of the strip lines 811 is connected to one of the switching elements 121, the other of the strip lines 811 is connected to one of the strip lines 812, and the other of the strip lines 812 is connected to one of the strip lines 813. . The other end of the strip line 813 is connected to the switching element 122.
[0207]
Further, the phase of this circuit part is adjusted in the same manner as in the third embodiment.
[0208]
That is, the relationship between the impedance value of the strip line 811, the impedance value of the strip line 812, and the impedance value of the strip line 813 is 1: a: a²Are in a relationship. However, a is adjusted to a predetermined value smaller than 1. That is, a is designed in advance so as to have the same phase delay amount as the phase delay amount of the reception signal output from the output terminal P2 with respect to the phase of the reception signal input from the input terminal P1 in the high gain mode. Value. The value of a can be determined in the same manner as described above.
[0209]
Accordingly, by passing through this circuit portion, a signal having a phase delay amount substantially the same as the delay amount of the passing phase in the high gain mode is output from the output terminal P2.
[0210]
As described above, even when the passing phase of the received signal in the high gain mode is delayed and the input impedance of the portion corresponding to the amplifier 13 is larger than the output impedance of the portion, the high gain mode is changed to the low gain mode. It is possible to sufficiently reduce the discontinuous change in the phase of the signal output from the output terminal P2 when switching to or from the low gain mode to the high gain mode.
[0211]
Instead of the strip lines 811, 812, 813, a taper having a taper whose characteristic impedance changes from Z1 to Z4 may be used.
[0212]
Note that the variable gain amplifying apparatus 37 of the present embodiment may also be configured such that at least one end of the switching elements 121, 122, and 123 has a zero potential, similarly to the variable gain amplifying apparatus 30 of the third embodiment. Thereby, the switching element is reliably turned on / off, and the insertion loss at the time of on is improved.
[0213]
Note that the variable gain amplifying device 37 can also be constituted by a balanced circuit as described in the third embodiment.
[0214]
  (Fifth embodiment)
  next,Of the invention related to the present inventionA fifth embodiment will be described.
[0215]
FIG. 14 shows a circuit diagram of a variable gain amplifying apparatus 38 according to the fifth embodiment.
[0216]
The variable gain amplifying apparatus 38 of the present embodiment is configured such that a portion corresponding to the phase shifter 15 of FIG.
[0217]
The variable gain amplifying apparatus 38 corresponds to a balanced variable gain amplifying apparatus 32 according to the third embodiment in which a portion corresponding to the phase shifter 15 is replaced with two parallel lines.
[0218]
Thus, the variable gain amplifying apparatus 38 according to the present embodiment has a balanced circuit.
[0219]
The same parts as those in the third embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
[0220]
The variable gain amplifying device 38 is such that the reception signal passing phase in the high gain mode is delayed, and the input impedance of the portion corresponding to the amplifier 13 is smaller than the output impedance of that portion.
[0221]
A portion of the variable gain amplifying apparatus 38 corresponding to the phase shifter 15 in FIG. 4 is composed of two parallel lines 911a and 911b, two parallel lines 912a and 912b, and two parallel lines 913a and 913b. One of the parallel two lines 911a and 911b is connected to the switching elements 121a and 121b, and the other is connected to one of the parallel two lines 912a and 912b. The other of the parallel two lines 912a and 912b is connected to one of the parallel two lines 913a and 913b, respectively. The other of the parallel two lines 913a and 913b is connected to the switching elements 122a and 122b, respectively.
[0222]
Further, the parallel two lines 911a and 911b, the parallel two lines 912a and 912b, and the parallel two lines 913a and 913b are each formed of an aluminum wire. In addition, the parallel two lines 911a and 911b, the parallel two lines 912a and 912b, and the parallel two lines 913a and 913b can be configured by copper wiring or gold wiring.
[0223]
Next, the operation of the present embodiment will be described focusing on the differences from the third embodiment.
The circuit portion functioning as the phase shifter 15 in FIG. 4 adjusts the phase as in the third embodiment.
[0224]
  That is, the interval between the parallel two lines 911a and 911b,Row 2The relationship between the distance between the lines 912a and 912b and the distance between the parallel two lines 913a and 913b is 1: a: a²Are in a relationship. However, a is adjusted to a predetermined value smaller than 1. That is, a has the same phase delay amount as the phase delay amount of the reception signals output from the output terminals P2a and P2b with respect to the phase of the reception signals input from the input terminals P1a and P1b in the high gain mode. It is a value designed in advance.
[0225]
Since the input / output impedance of the two parallel lines is determined by the line width, a can be determined in the same manner as the strip line described in the fourth embodiment.
[0226]
  Therefore, by passing through this circuit portion, a signal having a phase delay amount substantially the same as the delay amount of the passing phase in the high gain mode is output to the output terminal P2a,P2b.
[0227]
As described above, even when the passing phase of the received signal in the high gain mode is delayed and the input impedance of the portion corresponding to the amplifier 13 is smaller than the output impedance of the portion, the high gain mode is changed to the low gain mode. It is possible to sufficiently reduce the phase of the signals output from the output terminals P2a and P2b from changing discontinuously when switching to or from the low gain mode to the high gain mode.
[0228]
Note that the input / output ratio of the line width is 1: a instead of the parallel two lines 911a, 911b, 912a, 912b, 913a, 913b.²Two lines whose line width is gradually changed may be used.
[0229]
Note that the variable gain amplifying apparatus 38 of the present embodiment may have a configuration in which at least one end of the switching elements 121, 122, and 123 has a zero potential, similarly to the variable gain amplifying apparatus 30 of the third embodiment. Thereby, the switching element is reliably turned on / off, and the insertion loss at the time of on is improved.
[0230]
Further, when the input impedance of the portion corresponding to the amplifier 13 is larger than the output impedance of the portion and the passing phase of the received signal is delayed, the circuit portion corresponding to the phase shifter 15 in FIG. 4 is changed as follows. Then, the same effect as this embodiment can be obtained.
[0231]
That is, the variable gain amplifying device 39 in FIG. 15 has a delayed passage phase of the received signal in the high gain mode, and the input impedance of the portion corresponding to the amplifier 13 in FIG. 4 is larger than the output impedance of that portion. is there.
[0232]
The portion corresponding to the phase shifter 15 in FIG. 4 in the variable gain amplifying apparatus 39 is configured by two parallel lines 1011a and 1011b, two parallel lines 1012a and 1012b, and two parallel lines 1013a and 1013b. One of the parallel two lines 1011a and 1011b is connected to the switching elements 121a and 121b, and the other is connected to one of the parallel two lines 1012a and 1012b. The other of the parallel two lines 1012a and 1012b is connected to one of the parallel two lines 1013a and 1013b, respectively. The other of the parallel two lines 1013a and 1013b is connected to the switching elements 122a and 122b, respectively.
[0233]
Further, the phase of this circuit part is adjusted in the same manner as in the third embodiment.
[0234]
  That is, each line of the parallel two lines 1011a and 1011bShinoInterval and flatRow 2The relationship between the distance between the lines 1012a and 1012b and the distance between the parallel two lines 1013a and 1013b is 1: a: a²Are in a relationship. However, a is adjusted to a predetermined value larger than 1. That is, a has the same phase delay amount as the phase delay amount of the reception signals output from the output terminals P2a and P2b with respect to the phase of the reception signals input from the input terminals P1a and P1b in the high gain mode. It is a value designed in advance. Since the input / output impedance of the two parallel lines is determined by the line width, a can be determined in the same manner as the strip line described in the fourth embodiment.
[0235]
Therefore, by passing through this circuit portion, a signal having a phase delay amount substantially the same as the delay amount of the passing phase in the high gain mode is output from the output terminals P2a and P2b.
[0236]
As described above, even when the passing phase of the received signal in the high gain mode is delayed and the input impedance of the portion corresponding to the amplifier 13 is larger than the output impedance of the portion, the high gain mode is changed to the low gain mode. It is possible to sufficiently reduce the phase of the signals output from the output terminals P2a and P2b from changing discontinuously when switching to or from the low gain mode to the high gain mode.
[0237]
Note that the input / output ratio of the line width is 1: a instead of the parallel two lines 1011a, 1011b, 1012a, 1012b, 1013a, and 1013b.²Two lines whose line width is gradually changed may be used.
[0238]
Note that the variable gain amplifying device 39 of the present embodiment may also be configured such that at least one end of the switching elements 121, 122, and 123 has a zero potential, similarly to the variable gain amplifying device 30 of the third embodiment. Thereby, the switching element is reliably turned on / off, and the insertion loss at the time of on is improved.
[0239]
  (Sixth embodiment)
  next,Of the present inventionA sixth embodiment will be described.
[0240]
FIG. 16 shows a circuit diagram of the variable gain amplifying apparatus 40 of the sixth embodiment.
[0241]
In the variable gain amplifying apparatus 40 of the present embodiment, a portion corresponding to the phase shifter 15 of FIG. 4 is configured with a capacitor and an inductor.
[0242]
The same parts as those in the third embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
[0243]
In the variable gain amplifying apparatus 40 of the present embodiment, the passing phase of the received signal advances in the high gain mode, and the input impedance of the portion corresponding to the amplifier 13 is smaller than the output impedance of that portion.
[0244]
Further, the portion corresponding to the phase shifter 15 of FIG. 4 is different from the variable gain amplifying apparatus 33 of the third embodiment.
[0245]
That is, the portion corresponding to the phase shifter 15 in FIG. 4 includes capacitors 1114, 1115, and 1116 and inductors 1111, 1112, and 1113. In the variable gain amplifying apparatus 40, the passing phase of the received signal advances in the high gain mode, and the input impedance of the portion corresponding to the amplifier 13 is smaller than the output impedance of that portion.
[0246]
  In the variable gain amplifying apparatus 40, the portion corresponding to the phase shifter 15 of FIG. 4 has one of the switching elements 121 connected to one of the capacitors 1114 and one of the capacitors 1114 connected to the grounded inductor 1111. Yes. The other end of the capacitor 1114 is connected to the grounded inductor 1112 and one end of the capacitor 1115 is connected. The other end of the capacitor 1115 is a grounded inductor.1113And one of the capacitors 1116 are connected. One end of the switching element 122 is connected to the other end of the capacitor 1116.
[0247]
The inductors 1111, 1112, and 1113 are made of aluminum wiring, the capacitors 1114, 1115, and 1116 are made of MOS capacitors, and the wiring connecting the capacitors and the inductor is made of gold wiring. Inductors 1111, 1112, and 1113 may be made of copper wiring, and capacitors 1114, 1115, and 1116 may be made of MIM capacitors.
[0248]
Next, the operation of the present embodiment will be described with a focus on differences from the third embodiment.
[0249]
In the variable gain amplifying apparatus 40, the circuit portion that functions as the phase shifter 15 in FIG. 4 adjusts the phase as in the third embodiment.
[0250]
That is, the relationship between the inductance value of the inductor 1111, the inductance value of the inductor 1112, and the inductance value of the inductor 1113 is 1: a: a²Are in a relationship. The capacitance value of the capacitor 1114 and the relationship between the capacitance value of the capacitor 1115 and the capacitance value of the capacitor 1116 are expressed as follows:²: A: 1 relationship. However, a is adjusted to a predetermined value larger than 1. That is, a is adjusted in advance so as to have the same phase advance amount as the phase advance amount of the reception signal output from the output terminal P2 with respect to the phase of the reception signal input from the input terminal P1 in the high gain mode. Value. The determination of the value of a is the same as the method of determining a described in the third embodiment, in which the resistor is replaced with an inductor. In addition, since an inductor is used instead of the resistor of the third embodiment, the passage loss is smaller than that of the third embodiment.
[0251]
Therefore, by passing through this circuit portion, a signal having a phase advance amount substantially the same as the advance amount of the passing phase in the high gain mode is output from the output terminal P2.
[0252]
As described above, even if the passing phase of the received signal in the high gain mode is advanced and the input impedance of the portion corresponding to the amplifier 13 is smaller than the output impedance of the portion, the high gain mode is changed to the low gain mode. It is possible to sufficiently reduce the discontinuous change in the phase of the signal output from the output terminal P2 when switching to or from the low gain mode to the high gain mode.
[0253]
Note that the variable gain amplifying apparatus 40 of the present embodiment may have a configuration in which at least one end of the switching elements 121, 122, and 123 has a zero potential, similarly to the variable gain amplifying apparatus 30 of the third embodiment. Thereby, the switching element is reliably turned on / off, and the insertion loss at the time of on is improved.
[0254]
Although the variable gain amplifying apparatus 40 of the present embodiment has been described as an unbalanced circuit, it can also be realized as a balanced circuit.
[0255]
  That is, FIG. 17 shows the variable gain amplifying device of this embodiment.401 shows a variable gain amplifying device 41 realized as a balanced circuit.
[0256]
In the variable gain amplifying apparatus 41 of FIG. 17, the portions corresponding to the phase shifter 15 of the variable gain amplifying apparatus 32 of the third embodiment are capacitors 1114a, 1114b, 1115a, 1115b, 1116a, 1116b and inductors 1111, 1112, 1113 is replaced. The rest is the same as in the third embodiment.
[0257]
As described above, even when the variable gain amplifying apparatus 41 having a balanced circuit is used, the same effect as that of the present embodiment can be obtained.
[0258]
In the variable gain amplifying device 41 of FIG. 17, when the received signal passes through the circuit portion corresponding to the amplifier 13 of FIG. 4 when used in the high gain mode, the received signal input to the input terminal P1 The case where the phase of the received signal output from the output terminal P2 is advanced from the phase and the input impedance to the base of the transistor 101 is smaller than the output impedance of the collector of the transistor 102 has been described, but corresponds to the amplifier 13 of FIG. When the characteristics of the circuit part to be performed are other than that, it is necessary to change the circuit part corresponding to the phase shifter 15 of FIG.
[0259]
First, FIG. 18 shows a circuit diagram of a variable gain amplifying apparatus 42 in which a circuit portion corresponding to such a phase shifter 15 is changed. In the variable gain amplifying apparatus 42, the passing phase of the received signal in the high gain mode advances, and the input impedance of the portion corresponding to the amplifier 13 is larger than the output impedance of that portion.
[0260]
In the variable gain amplifying apparatus 42, the portion corresponding to the phase shifter 15 of FIG. 4 is connected to one of the switching elements 121 with one of the capacitors 1314 and the other of the capacitors 1314 with the grounded inductor 1311. At the same time, it is connected to one of the capacitors 1315. The other end of the capacitor 1315 is connected to the grounded inductor 1312 and to one end of the capacitor 1316. The other end of the capacitor 1316 is connected to the grounded inductor 1313 and to one of the switching elements 122.
[0261]
In the variable gain amplifying apparatus 42, the circuit portion functioning as the phase shifter 15 in FIG. 4 adjusts the phase in the same manner as in the third embodiment.
[0262]
That is, the relationship between the inductance value of the inductor 1311, the inductance value of the inductor 1312, and the inductance value of the inductor 1313 is 1: a: a²Are in a relationship. Further, the relationship between the capacitance value of the capacitor 1314, the capacitance value of the capacitor 1315, and the capacitance value of the capacitor 1316 is a²: A: 1 relationship. However, a is adjusted to a predetermined value smaller than 1. That is, a is designed in advance so as to have the same phase advance amount as the phase advance amount of the reception signal output from the output terminal P2 with respect to the phase of the reception signal input from the input terminal P1 in the high gain mode. Value. The determination of the value of a is the same as the method of determining a described in the third embodiment, in which the resistor is replaced with an inductor. In addition, since an inductor is used instead of the resistor of the third embodiment, the passage loss is smaller than that of the third embodiment.
[0263]
Therefore, by passing through this circuit portion, a signal having a phase advance amount substantially the same as the advance amount of the passing phase in the high gain mode is output from the output terminal P2.
[0264]
As described above, even if the passing phase of the reception signal in the high gain mode is advanced and the input impedance of the portion corresponding to the amplifier 13 is larger than the output impedance of the portion, the high gain mode is changed to the low gain mode. It is possible to sufficiently reduce the discontinuous change in the phase of the signal output from the output terminal P2 when switching to or from the low gain mode to the high gain mode.
[0265]
Note that the variable gain amplifying apparatus 42 of the present embodiment may have a configuration in which at least one end of the switching elements 121, 122, and 123 becomes 0 potential, similarly to the variable gain amplifying apparatus 30 of the third embodiment. Thereby, the switching element is reliably turned on / off, and the insertion loss at the time of on is improved.
[0266]
Note that the variable gain amplifying apparatus 42 of the present embodiment can also be configured by a balanced circuit as described in the present embodiment.
[0267]
FIG. 19 shows a circuit diagram of another variable gain amplifying device 43 in which the circuit portion corresponding to the phase shifter 15 is changed. The variable gain amplifying device 43 of FIG. 19 has a delayed passage phase of the received signal in the high gain mode, and the input impedance of the portion corresponding to the amplifier 13 is smaller than the output impedance of that portion.
[0268]
That is, in the portion corresponding to the phase shifter 15 in FIG. 4, one of the inductors 1414 is connected to one of the switching elements 121, the grounded capacitor 1411 is connected to one of the inductors 1414, and the other of the inductors 1414 is connected. One end of an inductor 1415 is connected to the capacitor 1412 and a grounded capacitor 1412 is connected to the capacitor 1412. A grounded capacitor 1413 is connected to the other side of the inductor 1415, and the other side of the inductor 1415 is connected to one side of the inductor 1416. One end of the switching element 122 is connected to the other end of the inductor 1416.
[0269]
The circuit portion functioning as the phase shifter 15 in FIG. 4 adjusts the phase as in the present embodiment.
[0270]
  That is, the inductance of the inductor 1414ValueAnd the relationship between the inductance value of the inductor 1415 and the inductance value of the inductor 1416 is 1: a: a²Are in a relationship. The capacitance value of the capacitor 1411 and the relationship between the capacitance value of the capacitor 1412 and the capacitance value of the capacitor 1413 are expressed as follows: a²: A: 1 relationship. However, a is adjusted to a predetermined value larger than 1. That is, a is designed in advance so as to have the same phase delay amount as the phase delay amount of the reception signal output from the output terminal P2 with respect to the phase of the reception signal input from the input terminal P1 in the high gain mode. Value. The determination of the value of a is the same as the method of determining a described in the third embodiment, in which the resistor is replaced with an inductor. In addition, since an inductor is used instead of the resistor of the third embodiment, the passage loss is smaller than that of the third embodiment.
[0271]
Accordingly, by passing through this circuit portion, a signal having a phase delay amount substantially the same as the delay amount of the passing phase in the high gain mode is output from the output terminal P2.
[0272]
As described above, even when the passing phase of the received signal in the high gain mode is delayed and the input impedance of the portion corresponding to the amplifier 13 is smaller than the output impedance of the portion, the high gain mode is changed to the low gain mode. It is possible to sufficiently reduce the discontinuous change in the phase of the signal output from the output terminal P2 when switching to or from the low gain mode to the high gain mode.
[0273]
Note that the variable gain amplifying apparatus 43 of the present embodiment may also be configured such that at least one end of the switching elements 121, 122, 123 has a zero potential, similarly to the variable gain amplifying apparatus 30 of the third embodiment. Thereby, the switching element is reliably turned on / off, and the insertion loss at the time of on is improved.
[0274]
Note that the variable gain amplifying apparatus 43 of the present embodiment can also be configured by a balanced circuit as described in the present embodiment.
[0275]
FIG. 20 shows a circuit diagram of another variable gain amplifying apparatus 44 in which the circuit portion corresponding to the phase shifter 15 is changed. The variable gain amplifying device 44 of FIG. 20 has a delayed passage phase of the received signal in the high gain mode, and the input impedance of the portion corresponding to the amplifier 13 is larger than the output impedance of that portion.
[0276]
In the portion corresponding to the phase shifter 15 in FIG. 4, one of the inductors 1514 is connected to one of the switching elements 121, and the grounded capacitor 1511 is connected to the other of the inductor 1514 and the other of the inductor 1514 is connected to the other. Is connected to one of the inductors 1515. A grounded capacitor 1512 is connected to the other side of the inductor 1515, and the other side of the inductor 1515 is connected to one side of the inductor 1516. A grounded capacitor 1513 is connected to the other end of the inductor 1516, and one of the switching elements 122 is connected to the other end of the inductor 1516.
[0277]
The circuit portion functioning as the phase shifter 15 in FIG. 4 adjusts the phase as in the present embodiment.
[0278]
That is, the relationship between the inductor value of inductor 1514, the inductor value of inductor 1515, and the inductor value of inductor 1516 is 1: a: a²Are in a relationship. The capacitance value of the capacitor 1511 and the relationship between the capacitance value of the capacitor 1512 and the capacitance value of the capacitor 1513 are expressed as follows: a²: A: 1 relationship. However, a is adjusted to a predetermined value smaller than 1. That is, a is designed in advance so as to have the same phase delay amount as the phase delay amount of the reception signal output from the output terminal P2 with respect to the phase of the reception signal input from the input terminal P1 in the high gain mode. Value. The determination of the value of a is the same as the method of determining a described in the third embodiment, in which the resistor is replaced with an inductor. In addition, since an inductor is used instead of the resistor of the third embodiment, the passage loss is smaller than that of the third embodiment.
[0279]
Accordingly, by passing through this circuit portion, a signal having a phase delay amount substantially the same as the delay amount of the passing phase in the high gain mode is output from the output terminal P2.
[0280]
As described above, even when the passing phase of the received signal in the high gain mode is delayed and the input impedance of the portion corresponding to the amplifier 13 is larger than the output impedance of the portion, the high gain mode is changed to the low gain mode. It is possible to sufficiently reduce the discontinuous change in the phase of the signal output from the output terminal P2 when switching to or from the low gain mode to the high gain mode.
[0281]
Note that the variable gain amplifying apparatus 44 of the present embodiment may also be configured such that at least one end of the switching elements 121, 122, 123 has a zero potential, similarly to the variable gain amplifying apparatus 30 of the third embodiment. Thereby, the switching element is reliably turned on / off, and the insertion loss at the time of on is improved.
[0282]
Note that the variable gain amplifying device 44 can also be configured by a balanced circuit as described in the present embodiment.
[0283]
  (Seventh embodiment)
  next,Of the invention related to the present inventionA seventh embodiment will be described.
[0284]
FIG. 27 shows the wireless communication apparatus of this embodiment. In the figure, a cellular phone terminal includes an antenna 1, an antenna duplexer 2, a transmission circuit unit 3, a variable gain amplification device 4, a mixer 7, a filter 8, a demodulator 2711, a baseband signal processing circuit 2712, and a signal level detection circuit 2713. And a control circuit 2714. The variable gain amplifying device 4, the mixer 7, the filter 8, the demodulator 2711, and the baseband signal processing circuit 2712 constitute a receiving circuit unit.
[0285]
Since the antenna 1 to the filter 8 are the same as those in the prior art, description thereof is omitted. The demodulator 2711 is a circuit that demodulates the baseband signal from the signal output from the filter 8. The baseband signal processing circuit 2712 is a circuit that processes the demodulated signal as digital data. The signal level detection circuit 2713 is a circuit that detects the input or output signal level of the mixer 7. The control circuit 2714 is a circuit for switching the variable gain amplifying device 4 to the high gain mode or the low gain mode according to the level of the signal level detection circuit 2713.
[0286]
  In addition, the variable gain amplifying apparatus 4 is the present invention.And inventions related to the present invention,This is a variable gain amplifying apparatus according to the first to sixth embodiments.
[0287]
Next, the operation of the wireless communication apparatus according to this embodiment will be described.
[0288]
A received signal received by the antenna 1 is amplified by the variable gain amplifying device 4 via the antenna duplexer 2. The mixer 7 converts the reception signal amplified by the variable gain amplifier 4 into an intermediate frequency signal, and the filter 8 reduces unnecessary frequency components of the converted intermediate frequency signal. The demodulator 2711 converts the intermediate frequency signal into an IQ baseband signal, and the baseband signal processing circuit 2712 restores the baseband signal to digital audio data in the baseband part.
[0289]
  The signal level detection circuit 2713 detects the signal level of the input or output of the mixer 7. When the control circuit 2714 receives the level detection signal from the signal level detection circuit 2713 and determines that the received signal level is high, the control circuit 2714 stops supplying the power supply voltage for operating the amplifier of the variable gain amplifying device 4. Variable gain amplifierFourThe switching element is controlled to be turned on. Therefore, a large received signal input from the antenna duplexer 2 is output to the mixer 7 through the switching element of the variable gain amplifier 4 without being amplified by the amplifier of the variable gain amplifier 4. That is, the variable gain amplifying device 4 operates with a low gain.
[0290]
On the other hand, when it is determined that the received signal level is low, the power supply voltage for operating the amplifier of the variable gain amplifying device 4 is supplied, and the switching element of the variable gain amplifying device 4 is controlled to be turned off. . Accordingly, the weak received signal input from the antenna duplexer 2 is amplified by the amplifier of the variable gain amplifying device 4 without passing through the switching element of the variable gain amplifying device 4 and is output to the mixer 7. That is, the variable gain amplifying apparatus 4 operates with a high gain.
[0291]
  In this case, the variable gain amplifying apparatus 4 is used as the present invention.And inventions related to the present inventionFrom the first of6thWhen the variable gain amplifying device 4 is switched from the low gain mode to the high gain mode, or when the variable gain amplifying device 4 is switched from the high gain mode to the low gain mode, the variable gain amplifying device is used. 4 can realize a radio communication apparatus that can normally demodulate a phase-modulated signal without the phase of the signal output from 4 changing discontinuously.
[0292]
In addition, there is an advantage that the response to a change in the signal level is quicker than in the case where the signal level detection circuit is connected downstream from the IF filter.
[0293]
In FIG. 27, level detection is performed at the input or output of the mixer 7, but level detection may be performed by the demodulator 2711 as shown in FIG. When both the desired wave and the disturbing wave are received at the input or output of the mixer 7, it is impossible to distinguish between the two. Therefore, in the radio communication apparatus of FIG. 27, although the level of the desired wave is low in some cases, the mode is switched to the low gain mode in response to the high level interference wave, and the desired wave is buried in noise and can be received correctly. There is a possibility of disappearing. On the other hand, in the configuration of FIG. 28, the level is detected by the demodulator 2711, which is the subsequent stage of the IF filter, so that the gain is switched according to the level of only the desired wave, and the above problem is solved.
[0294]
  In addition, as shown in FIG.signalThe processing circuit 2712 may detect the level digitally. With this configuration, the same effects as in FIG. 28 can be obtained and digital processing can be performed, so that level detection can be performed more easily.
[0295]
As shown in FIG. 30, level detection may be performed by both the input or output of the mixer 7 and the demodulator 2711. In the systems shown in FIGS. 28 to 29, when the desired wave level is low and the interference wave level is high, the mode is not switched to the low gain mode, so that the desired wave can be normally received normally. However, when an even larger interference wave enters, the amplifier of the variable gain amplifying apparatus 4 is saturated, resulting in a decrease in gain and a deterioration in noise figure, so that the desired wave may not be received correctly. On the other hand, in the configuration of FIG. 30, the mixer 7 detects the total level of the desired wave and the disturbing wave, and the demodulator 2711 detects the level of the desired wave. As a result, the desired wave level and the interference wave level are known. Here, when the desired wave level is below a certain level and the interference wave level is above a certain level, the above-mentioned problem is solved by increasing the current consumption of the amplifier.
[0296]
In FIG. 30, the reception signal level is detected before and after the IF filter, but the same effect can be obtained by detecting the reception signal level before and after the baseband filter.
[0297]
【The invention's effect】
  As is apparent from the above description, the present invention provides a variable gain that can sufficiently reduce the discontinuous change in the phase output from the variable gain amplifier even when the gain of the variable gain amplifier is switched. AmplificationPlaceCan be provided.
[Brief description of the drawings]
FIG. 1 shows the present invention.Inventions related toThe figure which shows the structure of the variable gain amplifier in 1st Embodiment of this
FIG. 2 shows the present invention.Inventions related toThe figure which shows the other structure of the variable gain amplifier in 1st Embodiment of this
FIG. 3 shows the present invention.Inventions related toThe figure which shows the other structure of the variable gain amplifier in 1st Embodiment of this
FIG. 4 shows the present invention.Inventions related toThe figure which shows the structure of the variable gain amplifier in 2nd Embodiment of this
FIG. 5 shows the present invention.Inventions related toThe figure which shows the other structure of the variable gain amplifier in 2nd Embodiment of this
FIG. 6 is a circuit diagram of a variable gain amplifying device according to a third embodiment of the present invention.
FIG. 7 is a circuit diagram of a variable gain amplifying apparatus having a balanced circuit according to a third embodiment of the present invention.
FIG. 8 is a circuit diagram of a variable gain amplifying apparatus having another configuration according to the third embodiment of the present invention.
FIG. 9 is a circuit diagram of a variable gain amplifying apparatus having another configuration according to the third embodiment of the present invention.
FIG. 10 is a circuit diagram of a variable gain amplifying apparatus having another configuration according to the third embodiment of the present invention.
FIG. 11 is a schematic diagram showing a cross-sectional configuration of a high-frequency switching element used in a variable gain amplifying device in a third embodiment of the present invention
FIG. 12 shows the present invention.Inventions related toThe circuit diagram of the variable gain amplifying apparatus using the stripline in 4th Embodiment of this invention
FIG. 13 shows the present invention.Inventions related toThe circuit diagram of the variable gain amplifier of another structure using the stripline in 4th Embodiment of this
FIG. 14 shows the present invention.Inventions related toThe circuit diagram of the variable gain amplifier using the parallel 2 line in 5th Embodiment of this invention
FIG. 15 shows the present invention.Inventions related toThe circuit diagram of the variable gain amplification apparatus of the other structure using the parallel 2 line in 5th Embodiment of this
FIG. 16 is a circuit diagram of a variable gain amplification device according to a sixth embodiment of the present invention.
FIG. 17 is a circuit diagram of a variable gain amplifying apparatus configured with a balanced circuit according to a sixth embodiment of the present invention;
FIG. 18 is a circuit diagram of a variable gain amplifying apparatus having another configuration according to the sixth embodiment of the present invention.
FIG. 19 is a circuit diagram of a variable gain amplifying apparatus having another configuration according to the sixth embodiment of the present invention.
FIG. 20 is a circuit diagram of a variable gain amplifying apparatus having another configuration according to the sixth embodiment of the present invention.
FIG. 21 is a diagram showing a configuration of a mobile phone terminal using a variable gain amplifier.
22A is a diagram plotting a set of values of a baseband I signal and a baseband Q signal demodulated when synchronization is performed by the quadrature demodulator, and FIG. 22B is synchronized by the quadrature demodulator. Of signal waveforms of baseband I signal and baseband Q signal demodulated when
23A is a diagram plotting a set of values of a baseband I signal and a baseband Q signal demodulated when synchronization is not achieved by the quadrature demodulator, and FIG. 23B is synchronized by the quadrature demodulator. The figure which shows the signal waveform of the baseband I signal demodulated when there is not, and a baseband Q signal
FIG. 24 is a configuration diagram of a microstrip line.
FIG. 25 (a) the present invention.Inventions related toThe figure which shows the structure of the variable gain amplifier of the other structure in 1st Embodiment of this, (b) this inventionInventions related toThe figure which shows the structure of the variable gain amplification apparatus of the other structure in 1st Embodiment of this
FIG. 26 shows the present invention.Inventions related toThe circuit diagram of the variable gain amplifier of the other structure of 4th Embodiment of this invention
FIG. 27 shows the present invention.Inventions related toThe block diagram which shows the structure of the radio | wireless communication apparatus of 7th Embodiment of
FIG. 28 shows the present invention.Inventions related toThe block diagram which shows the structure of the radio | wireless communication apparatus of 7th Embodiment of
FIG. 29 shows the present invention.Inventions related toThe block diagram which shows the structure of the radio | wireless communication apparatus of 7th Embodiment of
FIG. 30 shows the present invention.Inventions related toThe block diagram which shows the structure of the radio | wireless communication apparatus of 7th Embodiment of
[Explanation of symbols]
  13 Amplifier
  14 Switching elements
  15 Phase shifter
  16 input terminals
  17 Output terminal
  18 Variable gain amplifier
  19 Variable Gain Amplifier
  20 Switching element
  21 Variable gain amplifier
  22 Feedback circuit
  23 Switching element
  24 Variable Gain Amplifier
  25 Variable gain amplifier
  30 Variable Gain Amplifier
  31 Switching element power supply terminal
  32 Variable Gain Amplifier
  33 Variable Gain Amplifier
  34 Variable Gain Amplifier
  35 Variable Gain Amplifier
  36 Variable Gain Amplifier
  37 Variable Gain Amplifier
  101, 101a, 101b transistors
  102, 102a, 102b transistor
  103, 103a, 103b Inductor
  104, 104a, 104b Resistance
  105, 105a, 105b Negative feedback side capacitor
  106 Capacitor for bypass
  107 Bias power supply circuit
  108 Bias power supply circuit
  111, 112, 113 resistance
  114, 114a, 114b, 115, 115a, 115b, 116, 116a, 116b capacitors
  121, 121a, 121b, 122, 122a, 122b, 123, 123a, 123b switching element
  124, 124a, 124b inverter
  131, 131a, 131b Input side capacitor
  132, 132a, 132b Choke coil
  133, 133a, 133b Output side capacitor
  311, 312, 313 resistance
  314, 315, 316 capacitors
  411, 412, 413 capacitors
  414, 415, 416 resistance
  511, 512, 513 capacitors
  514, 515, 516 resistance
  601 Semiconductor substrate
  602 n-type well
  603 p-type well
  604 Gate insulating film
  605 Gate electrode
  606 Drain layer
  607 Source layer
  608 Trench part
  609 trench
  610, 611, 612 resistance
  P3 Voltage control terminal
  P10 input node
  P20 output node
  711, 712, 713 Strip line
  811, 812, 813 Strip line
  911a, 911b Line
  912a, 911b Line
  913a, 913b line
  1011a, 1011b line
  1012a, 1012b line
  1013a, 1013b line

Claims (2)

An amplifier;
A first switching element connected in parallel with the amplifier;
A phase shifter connected in series to the first switching element,
The phase shifter is a multistage circuit composed of n basic unit circuits (n is a natural number of 2 or more) composed of a capacitor and a resistor having one end connected to the capacitor and the other end grounded .
The basic unit circuit from the first stage to the n-th stage constituting the multi-stage circuit is such that the first stage basic unit circuit is connected to the first switching element, and the (i-1) stage (i is from 2 to n (natural number) of the basic unit circuit and the capacitor of the i-th basic unit circuit are connected in series ,
The resistance value of the resistor of the i-th basic unit circuit of the phase shifter is set to a times the resistance value of the resistor of the (i-1) -th basic unit circuit (a is a predetermined real number greater than 1). And the capacitance value of the capacitor of the i-th basic unit circuit is set to 1 / a times the capacitance value of the capacitor of the (i-1) -th basic unit circuit, whereby the input impedance of the phase shifter is set. | Z | (Z predetermined complex) the output impedance of the phase shifter a ⁿ · respect | Z | is set to, further,
Input impedance of the amplifier is the input impedance of the phase shifter | is set equal to the output impedance of the amplifier is a ⁿ · | | Z is set to, | Z
The first switching element is turned on when the level of the input signal or the output signal is higher than a predetermined level, and the level of the input signal or the output signal is equal to the predetermined level or the predetermined level If it is smaller, it is turned off.
The amplifier does not operate when the first switching element is in an on state, and operates when the first switching element is in an off state;
And advancing amount of phase when the input signal is passed through said amplifier, phase lead amount is equal variable gain amplifying apparatus in the case where the input signal has passed through said first switching element and the phase shifter. The first switching element is composed of a second switching element and a third switching element,
One of the second switching elements is connected to an input of the amplifier;
The other of the second switching elements is connected to one of the phase shifters,
The other of the phase shifters is connected to one of the third switching elements,
The variable gain amplifying apparatus according to claim 1, wherein the other of the third switching elements is connected to an output of the amplifier.