JP3710958B2 - Signal level control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a signal level control device used for a high frequency power amplifier, for example.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a signal level control device such as an ALC (Auto Level Controller) device used for a high frequency amplifier is a variable that can arbitrarily set an attenuation amount of a high frequency signal input to an input terminal 1, as shown in FIG. The attenuator 2a and n (n is a natural number) FETs (field effect transistors) 2b1 to 2bn are connected in series and amplified through the variable attenuator 2a. The signals are distributed at a predetermined ratio, and one of the distributed signals is output to the outside via the output terminal 4.
[0003]
On the other hand, the other signal distributed by the coupler 3 is half-wave rectified by the detector 5, smoothed by the low-pass filter (LPF) 6, and then supplied to the variable attenuator 2 a of the amplifier 2.
[0004]
Here, in the above configuration, when the amplitude level of the high-frequency signal input to the input terminal 1 varies, the amplitude level of the signal smoothed by the LPF 6 also varies, and the input control voltage applied to the variable attenuator 2a of the amplifier 2 increases. Thus, the power gain of the amplifier 2 is reduced. As a result, the amplitude level of the signal amplified by the amplifier 2 is kept substantially constant.
[0005]
However, in the above signal level control device, there is usually no problem when a high-frequency signal having a large time constant of the LPF 6 is handled, but the response speed of the device is slow when a pulsed high-frequency signal arrives. The amplitude level of the high-frequency signal will fluctuate from the beginning to the end of the pulse. Furthermore, there is a high possibility that it will not be able to respond at all to short pulses often used in radar devices and the like. Therefore, it is necessary to prepare a detector and an LPF that can cope with a pulsed high-frequency signal. In this case, however, the cost increases.
[0006]
[Problems to be solved by the invention]
As described above, in the conventional signal level control device, when a pulsed high-frequency signal arrives, the response speed of the device is slow, so that the amplitude level of the high-frequency signal fluctuates from the beginning to the end of the pulse. have. Further, it has a disadvantage that it is difficult to handle a short pulse high frequency signal often used in a radar apparatus or the like.
[0007]
An object of the present invention is to provide a signal level control device that can flexibly handle a continuous high frequency signal to a short pulse high frequency signal.
[0008]
[Means for Solving the Problems]
The signal level control apparatus according to the present invention includes a signal extraction / distribution unit that distributes a radar short pulse signal to two signals at a preset ratio, and attenuates one of the signals distributed by the signal extraction / distribution unit. Amplifying means for amplifying the quantity through a variable attenuator that can be arbitrarily set, and a signal amplified by the amplifying means are distributed to two signals at a preset ratio, and one of the distributed signals is externally provided. Output signal distribution output means, phase shift means for changing the phase of the other signal distributed by the signal extraction / distribution means to match the phase of the other signal distributed by the signal distribution output means, and 2 The mixed output of the two input signals, which has the maximum amplitude level when the phases of the two input signals match, is directly applied to the variable attenuator, and the time constant of the entire device determined by the frequency bandwidth of the mixed output is set to the minimum. OK Such comprising a balance type mixer, and the other signal distributed by the signal extracting distribution means in this balance type mixer inputs an output signal of the phase shifting means are mixed, attenuated giving the mixed output to the variable attenuator Attenuation control means for controlling the amount is provided.
[0009]
According to this configuration, a signal in a high frequency band is distributed into two signals at a predetermined ratio, and the distributed one signal is amplified through the variable attenuator and is variable with respect to the other distributed signal. A phase change is applied so that the phase shift from the signal amplified through the attenuator is small, and then the signal amplified through the variable attenuator is compared with the signal to which the phase change is applied. Determine whether the amplitude level is greater than the amplitude level of the amplified signal, and if it is greater than the result, control the attenuation of the variable attenuator so that the amplitude level of the signal to be amplified is reduced. Like to do.
[0010]
For this reason, the amplitude level of the signal amplified by the amplifier is kept almost constant even when the input high-frequency signal is fluctuated while the amplifier is thermally stable.
[0011]
Further, in the above configuration, the phase shift means is a means for changing the phase of the other signal distributed by the signal extraction / distribution means so that the phase of the other signal distributed by the signal distribution output means matches. The attenuation control means is a balanced mixer that mixes the signal obtained by the phase shift means and the other signal distributed by the signal distribution output means, and supplies the mixed output to the variable attenuator. To do.
[0012]
According to this configuration, the balanced mixer pays attention to outputting a signal having the maximum amplitude when the two signals to be mixed are in the same phase, so that the output amplitude of the balanced mixer is maximized. If the phase shift amount of the phase shifter is set according to the phase of the amplified signal, even if the amplitude level of the input high-frequency signal becomes larger than the known set value, the balance mixer The amplitude component of the output also increases, the input voltage of the variable attenuator increases, and the power gain of the amplifier is lowered, so that the amplitude level of the signal amplified by the amplifier is kept substantially constant. Even when a pulsed high frequency signal arrives, the frequency bandwidth of the output of a normal balanced mixer is wide, and the time constant of the entire device determined by the same frequency bandwidth can be set very small. The response speed to the high-frequency signal can be increased, whereby the amplitude level of the pulsed high-frequency signal amplified by the amplifier can be kept substantially constant.
[0013]
The signal level control apparatus according to the present invention also includes a signal extraction / distribution means for distributing a radar short pulse signal to two signals at a preset ratio, and one signal distributed by the signal extraction / distribution means. , Amplifying means for amplifying the amount of attenuation through a variable attenuator that can be arbitrarily set, and a signal amplified by this amplifying means are distributed in two at a preset ratio, and one of the distributed signals is externally A signal distribution output means for outputting to the signal, a phase shift means for giving a phase change to the other signal distributed by the signal extraction / distribution means by passing it through a variable phase shifter capable of arbitrarily setting the phase shift amount, The mixed output of the two input signals, which has the maximum amplitude level when the phases of the two input signals match, is directly applied to the variable attenuator, and the time constant of the entire device determined by the frequency bandwidth of the mixed output is set to the minimum. Possible balance A mixer is provided, and the output signal of the phase shift means and the other signal distributed by the signal distribution output means are input to this balanced mixer and mixed, and this mixed output is given to the variable attenuator to control the attenuation amount. and damping control means for, and the other signal distributed by the signal obtained and the signal distribution output means phase shift means and a phase comparator, transfers to control the amount of phase shift of the variable phase shifter on the basis of the comparison result And phase control means.
[0014]
According to this configuration, a signal in a high frequency band is distributed into two signals at a predetermined ratio, and the distributed one signal is amplified through the variable attenuator and is variable with respect to the other distributed signal. A phase change is applied so that the phase shift from the signal amplified through the attenuator is small, and then the signal amplified through the variable attenuator is compared with the signal to which the phase change is applied. It can be determined whether or not the amplitude level has become larger than the amplitude level of the amplified signal, and when the determination result is larger, the attenuation amount of the variable attenuator is controlled to be smaller. In addition, by comparing the phase of the signal given the phase change and the signal amplified through the variable attenuator, it is detected whether or not the phase shift amount of the amplifier has changed due to the change of the environmental temperature. The phase shift amount of the variable phase shifter is controlled based on the detection result.
[0015]
For this reason, even if the passage phase of the amplifier fluctuates due to a change in ambient temperature, the amplitude level of the signal amplified by the amplifier is kept almost constant.
[0016]
In the above configuration, the attenuation control means mixes the output of the first phase shift means and the other signal distributed by the signal distribution output means, and supplies the mixed output to the variable attenuator. The phase shift control means is obtained by the second phase shift means for shifting the phase of the signal obtained by the first phase shift means by 90 °, and the second phase shift means. And a second balanced mixer that mixes the signal and the other signal distributed by the signal distribution output means and supplies the mixed output to the variable phase shifter.
[0017]
According to this configuration, the phase shift amount of the variable phase shifter is controlled by the phase shifter having the phase shift amount of 90 ° so that the amplitude level of the output signal of the second balanced mixer is minimized. Yes. That is, when the passing phase shift amount of the amplifier changes, the amplitude level of the output signal of the second balanced mixer increases, and the control voltage of the variable phase shifter also increases. Therefore, the phase shift amount of the variable phase shifter changes so that the amplitude level of the output signal of the second balanced mixer is minimized, and at the same time the amplitude level of the output signal of the first balanced mixer is maximized. Become. Therefore, the circuit composed of the variable phase shifter, the phase shifter having a phase shift amount of 90 °, and the second balanced mixer functions as a temperature compensation circuit.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a circuit block diagram showing a configuration of an embodiment of a signal level control apparatus according to the present invention.
[0019]
In FIG. 1, a signal in a high frequency band (hereinafter referred to as a high frequency signal) input to the input terminal 11 is converted into a signal of an arbitrary amplitude level by the high frequency distributor 12 and 2 at a preset ratio. Divided into two signals. One signal distributed by the high-frequency distributor 12 is supplied to the amplifier 13. The amplifier 13 is configured by connecting a variable attenuator 13a capable of arbitrarily setting an attenuation amount and n (n is a natural number) FETs 13b1 to 13bn in series, and an input signal is passed through the variable attenuator 13a. Amplification is performed by the FETs 13b1 to 13bn. The signal amplified by the amplifier 13 is distributed into two signals at a preset ratio by the coupler 14, and then one of the distributed signals is taken out from the output terminal 15.
[0020]
On the other hand, the other signal distributed by the high frequency distributor 12 is supplied to the phase shifter 16. The phase shifter 16 changes the phase of the input signal so as to match the phase of the other signal distributed by the coupler 14 and outputs the input signal to the local oscillation input L 0 of the balanced mixer 17. The balanced mixer 17 inputs the other signal distributed by the coupler 14 to the high frequency input terminal RF, mixes the other signal and the output of the phase shifter 16, and mixes this mixed output with the intermediate frequency terminal IF. To the variable attenuator 13a of the amplifier 13 to control the attenuation amount of the variable attenuator 13a.
[0021]
The operation of the above configuration will be described below with reference to the diagram showing the phase-amplitude relationship in FIG.
First, in order to determine whether or not the amplitude level of the input high-frequency signal has become larger than a known set value, the signal distributed by the high-frequency distributor 12 is passed through the phase shifter 16 to the balance mixer 17. Input to local oscillator input LO. Further, the signal distributed by the coupler 14 is inputted to the high frequency input terminal RF of the balanced mixer 17.
[0022]
As shown in FIG. 2, the balanced mixer 17 outputs a signal having the maximum amplitude level when the two signals to be mixed have the same phase. 2, when the phase of the output of the phase shifter 16 with respect to the output of the coupler 14 is shifted by 90 ° or 270 °, the amplitude level of the output of the balanced mixer 17 decreases. Change. Therefore, the phase shifter 16 sets the phase shift amount according to the phase of the signal distributed by the coupler 14 so that the amplitude level of the output of the balanced mixer 17 is maximized. As a result, even when the amplitude level of the input high-frequency signal becomes larger than a known set value, the amplitude level of the output of the balanced mixer 17 also increases in accordance with the magnitude, and the input control voltage to the variable attenuator 13a. And the power gain of the amplifier 13 is lowered.
[0023]
As described above, according to the above-described embodiment, the high-frequency distributor 12 distributes a signal in the high-frequency band into two signals at a predetermined ratio, and the amplifier 13 transmits the distributed signal to the variable attenuator 13a. The signal is amplified and distributed to the two signals by the coupler 14 and one is output to the outside. The other signal distributed by the high-frequency distributor 12 is matched with the output phase of the coupler 14 by the phase shifter 16. Then, the balanced mixer 17 mixes the output of the phase shifter 16 and the output of the coupler 14 so that the amplitude level of the input signal is amplified by the amplifier 13, that is, known. It is possible to determine whether or not the value of the variable attenuator 13a is larger than the set value. If the determination result is larger, the attenuation amount of the variable attenuator 13a is controlled to be smaller.
[0024]
For this reason, the amplitude level of the signal amplified by the amplifier 13 is kept substantially constant even when the input high-frequency signal fluctuates while the amplifier 13 is thermally stable. Even when a pulsed high frequency signal arrives, the frequency bandwidth of the output of the balanced mixer 17 is usually wide, and the time constant of the entire device determined by the same frequency bandwidth can be set very small. The response speed with respect to the high frequency signal can be increased, and the amplitude level of the pulse high frequency signal amplified by the amplifier 13 can be kept substantially constant.
[0025]
Furthermore, in the above-described embodiment, the half-wave rectification and smoothing process is not required as in the prior art, and the balanced mixer 17 matches the output of the coupler 14 with the phase of the input signal matched to the output phase of the coupler 14. Since only the output of the phase shifter 16 needs to be mixed, the response speed can be improved as compared with the conventional case. Therefore, it is also suitable for a radar device.
[0026]
(Second Embodiment)
In the second embodiment of the present invention, a temperature compensation circuit for coping with a change in the characteristics of an amplifier due to a change in environmental temperature is added.
[0027]
FIG. 3 is a circuit block diagram showing the configuration of the signal level control apparatus according to the second embodiment. In FIG. 3, the same parts as those in FIG.
In this signal level control device, instead of the phase shifter 16, a variable phase shifter 21 whose phase shift amount can be arbitrarily set is connected, and high-frequency distribution is performed between the variable phase shifter 21 and the balanced mixer 17. A high frequency distributor 23 is interposed between the coupler 14 and the balanced mixer 17.
[0028]
Further, a phase shifter 24 having a phase shift amount of 90 ° is connected to the high frequency distributor 22, and a balanced mixer 25 is connected to the phase shifter 24. Further, a balanced mixer 25 is also connected to the high frequency distributor 23.
[0029]
The signal to which the phase change is given by the variable phase shifter 21 is distributed to two signals by the high frequency distributor 22, and one of the distributed signals is supplied to the local oscillation input terminal LO of the balanced mixer 17, and the other The signal is supplied to the phase shifter 24. The phase shifter 24 shifts the phase of the input signal by 90 ° and supplies it to the local oscillation input terminal LO of the balanced mixer 25. The balanced mixer 25 is supplied with the signal distributed by the high frequency distributor 23 to the high frequency input terminal RF. The balanced mixer 25 mixes the output of the high-frequency distributor 23 and the output of the phase shifter 24, and controls the phase shift amount of the variable phase shifter 21 based on the mixing result.
[0030]
The operation of the above configuration will be described below with reference to the diagram showing the phase-amplitude relationship in FIG.
First, in order to cope with a change in the characteristics of the amplifier 13 due to a change in the environmental temperature, the output of the variable phase shifter 21 is distributed by the high frequency distributor 22, and the phase of the distributed signal is 90 ° by the phase shifter 24. It is shifted and supplied to the local oscillation input terminal LO of the balanced mixer 25. Further, the signal distributed by the high frequency distributor 23 is supplied to the high frequency input terminal RF of the balanced mixer 25.
[0031]
The balanced mixer 25 controls the amount of phase shift of the variable phase shifter 21 based on the result of mixing the two signals so that the amplitude level of the output signal is minimized as shown in FIG. Here, since the phase relationship between the balanced mixer 17 and the balanced mixer is set to a fixed 90 ° relationship by the phase shifter 24 having a phase shift amount of 90 °, mixing is performed by the balanced mixer 17. If the two signals have the same phase, the phases of the two signals mixed by the balanced mixer 25 are shifted from each other by 90 °.
[0032]
In short, when the passing phase shift amount of the amplifier 13 changes, the amplitude level of the output signal of the balanced mixer 25 increases and the control voltage of the variable phase shifter 21 also increases. For this reason, the phase shift amount of the variable phase shifter 21 changes so that the amplitude level of the output signal of the balanced mixer 25 is minimized, and at the same time, the amplitude level of the output signal of the balanced mixer 17 is maximized. Change. Therefore, the circuit composed of the variable phase shifter 21, the high frequency distributors 22 and 23, the phase shifter 24, and the balanced mixer 25 functions as a temperature compensation circuit.
[0033]
As described above, according to the second embodiment, a signal in the high frequency band is distributed to two signals at a predetermined ratio by the high frequency distributor 12, and one of the distributed signals is the variable attenuator of the amplifier 13. 13a, and the other phase of the distributed signal is changed by the variable phase shifter 21 so that the phase shift from the output of the coupler 14 becomes small. By mixing the output and the output of the variable phase shifter 21, it can be determined whether the amplitude level of the incoming high-frequency signal has become larger than the amplitude level of the signal amplified by the amplifier 13, that is, a known set value. The attenuation amount of the variable attenuator 13a is controlled so as to be smaller when the determination result is larger. In addition, the signal whose phase change is given by the variable phase shifter 21 is mixed by the balanced mixer 25 with the signal whose phase is shifted by 90 ° and the output of the coupler 14. It is possible to detect whether or not there has been a change in the passage phase of the first and second phases, and the phase shift amount of the variable phase shifter 21 is controlled based on the detection result.
[0034]
For this reason, the amplitude level of the signal amplified by the amplifier 13 can be maintained substantially constant even if the passage phase of the amplifier 13 varies due to a change in environmental temperature.
[0035]
In the second embodiment, the function of the temperature compensation circuit is executed by a circuit composed of the variable phase shifter 21, the high frequency distributors 22 and 23, the phase shifter 24, and the balanced mixer 25. Although the example has been described, in addition to this, by comparing the phase of the output of the variable phase shifter 21 and the output of the coupler 14, it is detected whether or not the passing phase of the amplifier 13 has changed due to the change of the environmental temperature. The amount of phase shift of the variable phase shifter 21 may be controlled based on the detection result.
[0036]
(Other embodiments)
The present invention is not limited to the above embodiments. In each of the above embodiments, the balanced mixer 17 is used to control the amount of attenuation of the variable attenuator 13a. In addition, the balance mixer 17 is input by comparing the output of the phase shifter 16 with the output of the coupler 14. It is determined whether or not the amplitude level of the high frequency signal to be amplified is larger than the amplitude level amplified by the amplifier 13, and if this determination result is larger, the variable attenuator is set so that the amplitude level of the signal to be amplified becomes smaller. The amount of attenuation of 13a may be controlled. In addition, the phase shifter is not limited to the one in which the phase of the input signal matches the output phase of the coupler. Depending on the performance of the signal level control device, the phase difference between the input signal and the output phase of the coupler may be The amount of phase shift may be set so as to be small.
[0037]
In addition, the configuration of the high-frequency distributor, the configuration of the coupler, the type of the set phase shift amount of the phase shifter, and the like can be variously modified without departing from the gist of the present invention.
[0038]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to provide a signal level control apparatus that can flexibly handle a continuous high frequency signal to a short pulse high frequency signal.
[Brief description of the drawings]
FIG. 1 is a circuit block diagram showing a configuration of an embodiment of a signal level control apparatus according to the present invention.
2 is a view for explaining a phase-amplitude relationship in the balanced mixer shown in FIG. 1; FIG.
FIG. 3 is a circuit block diagram showing a configuration of a second embodiment of a signal level control apparatus according to the present invention;
4 is a diagram for explaining a phase-amplitude relationship in the balanced mixer shown in FIG. 3; FIG.
FIG. 5 is a circuit block diagram showing a configuration of a conventional signal level control device.
[Explanation of symbols]
1, 11 ... input terminals,
12, 22, 23 ... high frequency distributor,
2,13 ... Amplifier,
3, 14 ... coupler,
4, 15 ... output terminals,
16, 24 ... phase shifter,
17, 25 ... balanced mixer,
21 ... Variable phase shifter,
2a, 13a ... variable attenuator,
2b1-2bn, 13b1-13bn... FET.

Claims (2)

Signal extraction and distribution means for distributing a radar short pulse signal into two signals in a preset ratio;
Amplifying means for amplifying one of the signals distributed by the signal extraction / distribution means through a variable attenuator whose attenuation can be arbitrarily set;
A signal distribution output means for distributing the signal amplified by the amplification means into two signals at a preset ratio, and outputting one of the distributed signals to the outside;
Phase shifting means for changing the phase of the other signal distributed by the signal extraction / distribution means to match the phase of the other signal distributed by the signal distribution output means;
The mixed output of the two input signals, which has the maximum amplitude level when the phases of the two input signals coincide with each other, is directly supplied to the variable attenuator, and the time constant of the entire apparatus determined by the frequency bandwidth of the mixed output is obtained. A balanced mixer that can be set to a minimum is provided, and the other signal distributed by the signal distribution output means and the output signal of the phase shift means are input to the balanced mixer and mixed, and the mixed output is mixed with the mixed output. A signal level control device comprising attenuation control means for controlling the attenuation by giving to a variable attenuator. Signal extraction and distribution means for distributing a radar short pulse signal into two signals in a preset ratio;
Amplifying means for amplifying one of the signals distributed by the signal extraction / distribution means through a variable attenuator whose attenuation can be arbitrarily set;
A signal distribution output means for distributing the signal amplified by the amplification means into two at a preset ratio, and outputting one of the distributed signals to the outside;
Phase shifting means for giving a phase change to the other signal distributed by the signal extraction and distribution means by passing it through a variable phase shifter capable of arbitrarily setting the phase shift amount;
The mixed output of the two input signals, which has the maximum amplitude level when the phases of the two input signals coincide with each other, is directly supplied to the variable attenuator, and the time constant of the entire apparatus determined by the frequency bandwidth of the mixed output is obtained. A balanced mixer that can be set to a minimum is provided, and the output signal of the phase shift means and the other signal distributed by the signal distribution output means are input to the balanced mixer and mixed. Attenuation control means for controlling the amount of attenuation given to the variable attenuator,
Phase shift control means for comparing the phase of the signal obtained by the phase shift means and the other signal distributed by the signal distribution output means and controlling the phase shift amount of the variable phase shifter based on the comparison result A signal level control device comprising:

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