JP3495142B2 - Frequency conversion circuit - Google Patents

Description

Detailed Description of the Invention

(Table of contents) Industrial applications Conventional technology (Figs. 8 to 10) Problems to be Solved by the Invention (FIGS. 9 to 11) Means for solving the problems Action Example (FIGS. 1 to 7) The invention's effect

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for use in a mobile communication terminal such as a mobile phone or a radio frequency communication section in a base station accommodating the mobile communication terminal in a radio communication system such as a mobile communication system. A frequency conversion circuit.

[0003]

2. Description of the Related Art Generally, a radio device 120 for performing radio communication converts a signal into an RF signal as a high frequency input signal suitable for transmitting by spatial propagation, as shown in FIG. It has a high frequency transmitting section 100 for transmitting, a high frequency receiving section 110 for receiving the RF signal transmitted by the high frequency transmitting section 100 and demodulating the signal, a duplexer 104 and an antenna 105.

Here, the high frequency transmitting section 100 includes the modulating section 1
01, the up-converter 102 and the amplifier 103, the modulator 101 modulates the intermediate frequency signal (IF signal) in the encoded transmission signal (digital signal), and the up-converter 102 includes the modulator 1.
The converter 103 converts the modulated signal from 01 into an RF signal suitable for spatial propagation.
The RF signal from 2 is amplified.

Further, the up converter 102 includes a mixing circuit 102A and a voltage controlled oscillator (VCO) 102.
It has B. That is, the mixing circuit 102A
Then, the modulated signal from the modulator 101 and the local oscillation signal (LO signal) from the VCO 102B are input, and these signals are mixed to generate and output an RF signal.

The high frequency receiving section 110 includes a low noise amplifier (LNA) 111, a down converter 112, an amplifier 113 and a demodulating section 114.
1 is for low-noise amplification of an RF signal as a reception signal input via the antenna 105 and the duplexer 104, and the amplifier 113 is a down converter 1
The IF signal from 12 is amplified, and the demodulation unit 11
4 demodulates the IF signal amplified by the amplifier 113,
It is output as a coded reception signal (digital signal).

The down converter 112 is an LNA.
The signal received from 111 is converted into an IF signal, which includes a mixing circuit (frequency conversion circuit) 112A and a voltage controlled oscillator (VCO) 112B. That is, the receiving circuit from the LNA 111 and the LO signal from the VCO 112B are input to the mixing circuit 112A, and these signals are mixed to generate and output an IF signal.

With such a configuration, in the radio device 120 shown in FIG. 8, when transmitting a signal, an RF signal is transmitted via the high frequency transmitting section 100, the duplexer 104 and the antenna 105, while The RF signal is received via the antenna 105 and the duplexer 104 of the receiving wireless device. The received RF signal is LNA111
After being amplified by, it is input to the down converter 112,
By being mixed with the LO signal generated by the VCO 112B in the mixing circuit 112A, it is converted into an IF signal and output.

Here, as the mixing circuit 112A of the above-described down converter 112, a conventional mixing circuit 112A, for example, as shown in FIG.
The frequency conversion circuit 200 having a circuit configuration as shown in can be used. That is, as shown in FIG. 9, the frequency conversion circuit 200 has a single-ended configuration with the dual gate FET 204. Here, matching circuits 206 and 207 are connected to the first gate 201 and the second gate 202 of the dual gate FET 204, respectively. Matching circuits 206 and 207 are RF
Signals and LO signals are input, and these RF signals and LO signals are matched by performing signal processing. As a result, the RF signals and LO signals are dual gate F
It is designed to be efficiently input to ET204.

The matching circuit 206 has two capacitors 206A and 206C and an inductor 206B, and the matching circuit 207 has two capacitors 207.
It has A and 207C and an inductor 207B. In addition, the source 203 is a resistor 20 for one power source.
8 and a capacitor 209 for increasing the conversion gain. Further, the first gate 201, the second
The gate 202 is grounded via resistors 210 and 211, respectively.

Reference numeral 212 is an inductor, 213 is a capacitor, 214 is a power supply, and 215 is three capacitors 21.
This is a matching circuit including 5A, 215C and 215D and an inductor 215B. With this configuration,
In the dual gate FET 204, the matching circuit 20 is provided in the first gate 201, which is a gate close to the source 203.
RF signal is input via 6 and drain 2
In the second gate 202, which is a gate close to 05, the LO signal is input through the matching circuit 207 and R
The F signal and the LO signal are mixed and frequency-converted, and output from the drain 205 as an IF signal.

As the mixing circuit 112A of the down converter 112, a frequency conversion circuit 300 having a circuit configuration as shown in FIG. 10 can be used in addition to the one shown in FIG. That is, the frequency conversion circuit 300 is configured so that the bipolar transistor 30
4 has a single-ended configuration. Here, a matching circuit 306 and a transmission line 307, and a matching circuit 308 and a transmission line 309 are connected in parallel to the base 302 of the bipolar transistor 304.

That is, the matching circuit 306 and the transmission line 307 match the RF signal, and the matching circuit 308 and the transmission line 3 are matched.
09 matches the LO signal. Also,
The RF signal from the transmission line 307 and the LO signal from the transmission line 309 are combined at the combining point 301 and input to the base 302, whereby the RF signal and the LO signal are input.
The signal can be efficiently input to the bipolar transistor 304.

Further, the bipolar transistor 304
Matches the RF signal and the LO signal to the matching circuit 30 respectively.
6 and 308 are matched, and transmission lines 307 and 309 are isolated.
The RF signal and LO signal isolated by the transmission lines 307 and 309 are combined at the combining point 301 and input to the base 302, mixed in the bipolar transistor 304 for frequency conversion, and converted into an IF signal via the collector 305. It is designed to output.

The emitter 303 is grounded via a resistor 310 for one power supply and a capacitor 311 for increasing the conversion gain, and the base 302 is grounded via a resistor 312. 313 is a power source, 314 is a capacitor, 315 is an inductor, 316 is a resistor, 31
7 is three capacitors 317A, 317C and 317D
And a inductor 317B.

[0016]

By the way, the wireless device 120 as the above-mentioned mobile communication terminal is required to have a smaller size and a higher frequency. For this purpose, it is particularly necessary to make the characteristics of the down converter 112 high output and low distortion. However, as shown in FIG. 9 described above, when the frequency conversion circuit 200 as the mixing circuit 112A is configured using the dual gate FET 204, the third-order intermodulation distortion, which is important when used in communication equipment, is large ( That is, the input intercept point [IIP] becomes low), and there is a problem that noise occurs in adjacent channels.

Further, as shown in FIG. 10 described above, the mixing circuit 11 is formed by using the bipolar transistor 304.
When the frequency conversion circuit 300 as 2A is configured, the number of parts and the mounting area of the external circuit are increased in order to isolate the RF signal and the LO signal in the base 302. However, there was a problem that

On the other hand, Japanese Patent Application Laid-Open No. 61-224506 discloses a technique relating to a frequency conversion circuit for solving these problems. That is, this JP-A-6
In the technique disclosed in Japanese Patent Laid-Open No. 1-222406, FIG.
As shown in FIG. 1, the frequency conversion circuit 400 has a single-ended configuration with a single gate FET 403, and a filter 405 that cuts a high frequency signal component (noise component) is connected.

As a result, in the frequency conversion circuit 400 shown in FIG. 11, the gate 40 of the single gate FET 403 is
While the LO signal is input to 2, the high frequency signal component is cut by the filter 405, the RF signal is reduced in noise, and the RF signal is input to the source 401. Single gate FET 40
In 3, the RF signal and the LO input to the gate 402 are input.
The signal is mixed with the signal to convert the frequency, and the drain 404
To output as an IF signal.

That is, by using this single-gate FET 403, it is possible to reduce the third-order intermodulation distortion (to prevent the decrease of the input intercept point [IIP]), and to output the RF signal from the source 401 to the LO signal. By inputting signals from the gate 402 respectively, it is not necessary to obtain isolation. However, this single-gate FET 403 reduces the third-order intermodulation distortion (input intercept point [I
(IP) can be prevented), but the conversion gain decreases, so it is necessary to amplify the IF signal using an amplifier.

However, in the frequency conversion circuit 400 configured by using the single gate FET 403 as shown in FIG. 11, the drain 4 as the IF port is used.
Since the RF signal and the LO signal leak to 04, if the IF signal output from the drain 404 is amplified using an amplifier, the leaked RF signal and the LO signal are also amplified and output, resulting in a noise component. However, there is a problem in that a large number of IF signals are output and communication accuracy deteriorates.

The present invention was devised in view of the above problems, and reduces the third-order intermodulation distortion while realizing the miniaturization of the device with a simple circuit configuration (input intercept point [IIP]). To prevent deterioration) and R
It is an object of the present invention to provide a high-output and low-distortion frequency conversion circuit by preventing leakage of the F signal and LO signal and amplifying the IF signal.

[0023]

Therefore, in the frequency conversion circuit of the first invention, in the frequency conversion circuit for mixing the high frequency input signal and the local oscillation signal and outputting the intermediate frequency signal, the high frequency input signal is output. A first transistor for frequency conversion that outputs the intermediate frequency signal from the drain or collector by receiving at the source or emitter and at the gate or base at the gate or base, and in tandem connection with the first transistor to form the intermediate A second transistor for signal amplification for amplifying and outputting the frequency signal, and preventing the intermediate frequency signal from leaking to another place while transmitting the intermediate frequency signal from the second transistor. To supply to the gate or base ,
A predetermined operating point at the gate or base of the second transistor
Biased to obtain
In which has the characteristic of being open to the wave signal
And an intermediate frequency signal leakage prevention circuit and inductor is formed by features, the drain or collector of said first transistor
Is the source or the source of the second transistor via the inductor.
Is connected to the emitter and the first transistor
The drain or collector of the second capacitor via the capacitor
It is characterized by being connected to the gate or base of the transistor .

Further, the frequency conversion circuit of the second invention is a frequency conversion circuit which mixes a high frequency input signal and a local oscillation signal and outputs an intermediate frequency signal. A first transistor for frequency conversion that outputs the intermediate frequency signal from the drain or collector by receiving the local oscillation signal at the gate or the base, and is tandem-connected to the first transistor to amplify and output the intermediate frequency signal. A second transistor for amplifying a signal, and a voltage is applied to the gate or the base of the first transistor via a resistor, and the source or the emitter of the first transistor is an inductor. Grounded through the drain and collector of the first transistor and the second transistor. And the gate or the base of Njisuta is,
The drain or collector of the first transistor and the source or emitter of the second transistor are connected via a capacitor, and are connected via an inductor that is open to the intermediate frequency signal, and
A voltage is applied to the gate or the base of the second transistor via a resistor, and a voltage is applied to the drain or the collector of the second transistor via an inductor. (Claim 2).

Further, the frequency conversion circuit of the third invention is a frequency conversion circuit which mixes a high frequency input signal and a local oscillation signal to output an intermediate frequency signal, and receives the high frequency input signal at a source or an emitter and By receiving the local oscillation signal at the gate or base,
A first transistor for frequency conversion that outputs the intermediate frequency signal from a drain or a collector; and a second transistor for signal amplification that is tandem-connected to the first transistor and that amplifies and outputs the intermediate frequency signal, The gate or base of the first transistor is grounded via a resistor, and the source or emitter of the first transistor is grounded via a resistor. The drain or collector is directly connected to the gate or base of the second transistor, and the drain or collector of the first transistor and the source or emitter of the second transistor are connected to the second transistor. Source or emitter
High resistance to bias to get the desired operating point
Characteristics that are anti-resistance and hardly pass the intermediate frequency signal
And a voltage is applied to the drain or collector of the second transistor through an inductor (claim 3).

Further, the frequency conversion circuit of the fourth invention is a frequency conversion circuit which mixes a high frequency input signal and a local oscillation signal to output an intermediate frequency signal, and receives the high frequency input signal at a source or an emitter and A first transistor for frequency conversion that outputs the intermediate frequency signal from the drain or collector by receiving the local oscillation signal at the gate or the base, and is tandem-connected to the first transistor to amplify and output the intermediate frequency signal. And a second transistor for amplifying a signal, the gate or base of the first transistor is grounded via a resistor, and the source or emitter of the first transistor is connected to the high frequency input. Grounded through an inductor and a resistor that are open to the signal, and The drain or collector of the first transistor is directly connected to the gate or base of the second transistor, and the drain or collector of the first transistor and the source or emitter of the second transistor are connected to the intermediate frequency signal. Is connected to the drain or collector of the second transistor via an inductor, and a voltage is applied to the drain or collector of the second transistor via the inductor (claim 4).

The frequency conversion circuit of the second to fourth inventions may be provided with a capacitor for grounding the source or the emitter of the second transistor in high frequency (Claim 5). A capacitor for grounding the gate or the base of the second transistor in high frequency may be provided (claim 6), and a capacitor for grounding the source or the emitter of the second transistor in high frequency is provided, and A capacitor for grounding the gate or the base of the second transistor in high frequency may be provided (claim 7).

Further, in the frequency conversion circuit according to the fourth aspect of the present invention, even if the connection point between the inductor and the resistor connected to the source or the emitter of the first transistor is grounded via the capacitor. Often (claim 8) the source or emitter of the second transistor may be grounded via another resistor (claim 9).

[0029]

In the frequency conversion circuit of the first invention described above, first, the source or the emitter of the first transistor for frequency conversion receives a high frequency input signal, and the gate or the base receives a local oscillation signal, and the first transistor operates. The high frequency input signal and the local oscillation signal are mixed, and an intermediate frequency signal is output from the drain or the collector.

The intermediate frequency signal output from the drain or collector of the first transistor is prevented from leaking to another place by the intermediate frequency signal leakage prevention circuit. Then, a second amplifier for signal amplification is connected in tandem with the first transistor.
Predetermined operation from the first transistor to the gate or base of the second transistor by the gate or base of the transistor
Capacitors to bias to get points and intermediate
In which has the characteristic of being open to the wave signal
The intermediate frequency signal is received through the intermediate frequency signal leakage prevention circuit provided with the ductor, and the second transistor amplifies and outputs the intermediate frequency signal (claim 1).

In the frequency conversion circuit according to the second aspect of the invention, first, the gate or the base of the first transistor for frequency conversion receives the voltage applied by the power supply through the resistor and outputs the local oscillation signal. A source or emitter that receives and is grounded via an inductor receives a high frequency input signal, and the first transistor mixes the high frequency input signal with the local oscillation signal and outputs an intermediate frequency signal from the drain or collector. .

Then, the gate or the base of the second transistor for signal amplification, which is tandem-connected to the first transistor, receives the voltage applied by the power supply through the resistor, and further receives the intermediate frequency input from the first transistor. In addition to receiving the signal, the drain or collector of the second transistor receives the voltage applied by the power supply via the inductor, and the second transistor amplifies and outputs the intermediate frequency signal.

When the intermediate frequency signal is output from the drain or collector of the first transistor to the gate or base of the second transistor, the second transistor is opened by the inductor that is open to the intermediate frequency signal. The intermediate frequency signal is prevented from leaking to the source or the emitter (claim 2). Further, the frequency conversion circuit of the third invention described above, first, in the first transistor for frequency conversion, together with the receiving local oscillation signal at the gate or base is grounded through a resistor, second tiger
The source or emitter of the transistor
A high resistance and intermediate frequency signal for biasing
A high-frequency input signal is mixed with a local oscillation signal by receiving a high-frequency input signal with a source or emitter that is grounded via a resistor having a characteristic that almost does not pass through , and an intermediate-frequency signal is output from the drain or collector. To do.

Then, the gate or base of the second transistor for signal amplification, which is tandem-connected to the first transistor, receives the intermediate frequency signal from the first transistor, and the drain or collector of the second transistor passes through the inductor. It receives the voltage applied by the power source and amplifies and outputs this intermediate frequency signal. Further, when the intermediate frequency signal is output from the drain or collector of the first transistor to the gate or base of the second transistor, the resistance prevents the intermediate frequency signal from leaking to the source or the emitter ( Claim 3).

In the frequency conversion circuit of the above-mentioned fourth invention, first, in the first transistor for frequency conversion, the gate or the base grounded via the resistor receives the local oscillation signal and the high frequency input signal. A source or emitter that is grounded via an inductor and a resistor that are open to receive a high frequency input signal, mix the high frequency input signal and the local oscillation signal, and output an intermediate frequency signal from the drain or collector.

Then, the gate or the base of the second transistor for signal amplification, which is tandem-connected to the first transistor, receives the intermediate frequency signal from the first transistor, and the drain or collector of the second transistor passes through the inductor. It receives the voltage applied by the power source and amplifies and outputs this intermediate frequency signal. When an intermediate frequency signal is output from the drain or collector of the first transistor to the gate or base of the second transistor, the source and the emitter are connected to the source or emitter by an inductor and a resistor that are open to the intermediate frequency signal. The leakage of the intermediate frequency signal is prevented (Claim 4).

In the frequency conversion circuits of the above-mentioned second to fourth inventions, a capacitor for grounding the source or emitter of the second transistor in high frequency is provided to increase the amplification factor of the intermediate frequency signal. And a capacitor for grounding the gate or the base of the second transistor in a high frequency manner so that the high frequency input signal and the local oscillation signal leaked to the drain or the collector of the first transistor are transmitted to the second transistor. It is prevented from leaking to the gate or the base (claim 6).

By providing a capacitor for grounding the source or emitter of the second transistor in high frequency and a capacitor for grounding the gate or base of the second transistor in high frequency, the amplification factor of the intermediate frequency signal is increased. At the same time, the high frequency input signal and the local oscillation signal leaked to the drain or collector of the first transistor are prevented from leaking to the gate or base of the second transistor (claim 7).

Furthermore, in the frequency conversion circuit of the above-mentioned fourth invention, the connection point between the above-mentioned inductor connected to the source or the emitter of the first transistor and the resistor is grounded via the capacitor so that the source or The high frequency input signal input to the emitter is matched to increase the conversion gain in the first transistor (claim 8), and the source or emitter of the second transistor is grounded via a resistor. , The conversion gain in the second transistor is increased (claim 9).

[0040]

Embodiments of the present invention will be described below with reference to the drawings. (A) Description of the First Embodiment FIG. 1 is an electric circuit diagram showing a frequency conversion circuit according to the first embodiment of the present invention. The frequency conversion circuit shown in FIG. 1 has a high frequency input signal (RF signal). Local oscillation signal (LO
Signal) and an intermediate frequency signal (IF signal)
Is output and can be used as the mixing circuit 112A of the down converter 112 in FIG. 8 described above.

Here, 3A is a first transistor,
The first transistor 3A receives the RF signal at the source 1 and receives the LO signal at the gate 2, thereby mixing the RF signal and the LO signal for frequency conversion and outputting the IF signal from the drain 4 as an IF signal. is there. That is, in the first transistor 3A, the source 1 has R
Since the F signal is input, the LO signal is input to the gate 2, and the IF signal is output from the drain 4, the RF signal, the L signal, and the L signal are increased without increasing the number of components for forming the circuit.
Isolation between O signals and large signal characteristics are improved.

The gate 2 of the first transistor 3A
Is connected to a power source 6 via a resistor 5, and a voltage from the power source 6 is applied to the gate 2. Further, the source 1 is grounded via the inductor 7, but the inductor 7 has a characteristic that it is open to the RF signal, whereby the leakage of the RF signal input to the source 1 is caused. And to prevent signals having frequency components other than the RF band from being input to the source 1, thereby matching the RF signals.

Further, the drain 4 of the first transistor 3A is connected to the gate 9 of the second transistor 10A, which will be described later, via the capacitor 8 and also connected to the source 12 of the second transistor 10A via the inductor 11. There is. The second transistor 10A is connected in tandem with the first transistor 3A, and amplifies and outputs the IF signal from the first transistor 3A.

Here, the capacitor 8 biases the gate 9 of the second transistor 10A in order to obtain a predetermined operating point, and the inductor 11 has a characteristic of being open to the IF signal. As a result, the IF signal output from the first transistor 3A is
It is adapted to be input to the gate 9 of the second transistor 10A without leaking to the source 12 of the second transistor 10A.

That is, the capacitor 8 and the inductor 11
Thus, the intermediate-frequency signal leakage prevention circuit 60 that supplies the IF signal to the gate 9 of the second transistor 10A while preventing the leakage of the IF signal from the first transistor 3A to other places is configured. A power source 14 is connected to the gate 9 of the second transistor 10A via a resistor 13, and a voltage is applied to the gate 9 by the power source 14. Further, the drain 15 is connected to a power supply 17 via an inductor 16, and the drain 15
The voltage from the power source 17 is applied to the. In addition, the inductor 16 has a characteristic that it is open to the IF signal.
The amplified IF signal as the output of the drain 15 of the second transistor 10A is prevented from leaking to the power supply 17, and the IF signal is matched.

By the way, the gate 9 of the second transistor 10A is grounded at a high frequency by the capacitor 18, whereby the RF signal and the LO signal leaked to the drain 4 of the first transistor 3A are discharged to the ground, and the RF signal and The LO signal is the gate 9 of the second transistor 10A.
The input signal is prevented from being input to and the amplification characteristic of the IF signal is enhanced.

Further, the source 12 of the second transistor 10A is grounded at a high frequency by the capacitor 19, so that the RF and LO signals leaked to the drain 4 of the first transistor 3A are grounded like the capacitor 8 described above. This prevents discharge and input of RF and LO signals to the source 12 of the second transistor 10A, and enhances the IF amplification characteristic.

The above-mentioned grounded capacitor 18,
Reference numeral 19 is provided to increase reliability, and when designing a circuit, these can be omitted depending on the required circuit performance. With the above configuration, the frequency conversion circuit according to the first embodiment of the present invention operates as follows.

That is, when the RF signal is input to the source 1 of the first transistor 3A and the LO signal is input to the gate 2 of the first transistor 3A, and a voltage is applied to the gate 2 by the power supply 6, the first transistor 3A outputs the RF signal. The IF signal is output from the drain 4 by mixing the signal and the LO signal. The IF signal output from the drain 4 is supplied to the second transistor 10A by the intermediate frequency signal leakage prevention circuit 60.
Input to the gate 9 without leaking to the source 12 of the. Further, in the second transistor 10A, a voltage is applied to the gate 9 by the power supply 14 and a voltage is applied to the drain 15 by the power supply 17, and
The F signal is amplified and the amplified IF signal is output from the drain 15.

For example, the source 1 of the first transistor 3A
The frequency f _{RF of the} RF signal input to the terminal is 1.9 GHz, and the f _IF of the IF signal output from the drain 4 is 240 MHz.
In such a case, when the soft simulation is performed on the third-order distortion cross-modulation distortion characteristic, the characteristic as shown in FIG. 2 is obtained. That is, as shown at point A in FIG.
A characteristic having a high input intercept point [IIP] can be obtained by the first transistor 3A, the third-order distortion intermodulation distortion characteristic can be improved, and noise can be prevented from occurring in an adjacent channel.

In the first transistor 3A, the conversion gain of the IF signal decreases as the third-order distortion cross-modulation distortion characteristic is improved, but the second transistor 10A converts the IF signal whose conversion gain decreases. Since the gain is efficiently amplified, the gain reduction in the first transistor 3A is absorbed and the reduction in the conversion gain of the entire circuit is prevented, thereby realizing a high-output and low-distortion frequency conversion circuit. There is.

As described above, according to the frequency conversion circuit of the first embodiment of the present invention, the first transistor 3 for frequency conversion is used.
A and a second transistor 10A for amplifying a signal, and a resistor 5 is connected to the gate 2 of the first transistor 3A.
Is applied via the inductor 7, the source 1 of the first transistor 3A is grounded via the inductor 7,
Furthermore, the drain 4 of the first transistor 3A and the gate 9 of the second transistor 10A are connected via the capacitor 8 and the drain 4 of the first transistor 3A is connected.
And a source 12 of the second transistor 10A are connected via an inductor 11 which is open to an intermediate frequency signal, and a resistor 1 is connected to a gate 9 of the second transistor 10A.
3 is applied to the drain 15 of the second transistor 10A via the inductor 16, and the voltage is applied to the drain 15 of the second transistor 10A from the first transistor 3A to the second transistor 10A of the RF signal and the LO signal. The leakage of the IF signal from the first transistor 3A is prevented by the action of the intermediate frequency signal leakage prevention circuit 60, and the IF signal from the first transistor 3A is not leaked to another place.
This IF can be supplied to the gate 9 of A
Since signals can be matched, there is an advantage that high output and low distortion circuit characteristics can be obtained.

Furthermore, according to the frequency conversion circuit of this embodiment, the source 12 of the second transistor 10A is provided with the capacitor 19 grounded at high frequency, and the gate 18 of the second transistor 10A is grounded at high frequency. By effectively providing the RF signal and the LO signal leaked to the drain 4 of the first transistor 3A to the gate 9 of the second transistor 10A, the RF signal to the drain 15 as an IF port is provided. And the leakage of the LO signal is improved, and the second transistor 10
Since the amplification characteristic at A can be further improved, the number of matching circuit elements in the drain 15 of the second transistor 10A can be reduced, and a frequency conversion circuit with higher output and lower distortion while being compact can be realized. There are advantages.

According to the frequency conversion circuit of the present embodiment, the RF signal is input to the source 1 of the first transistor 3A and the LO signal is input to the gate 2 of the first transistor 3A.
Since the F signal is output, the large signal characteristic can be improved together with the isolation between the RF signal and the LO signal without increasing the number of components forming the circuit.
In the above-described embodiment, the capacitor 18 for grounding the gate 9 of the second transistor 10A in high frequency is provided, and the capacitor 19 for grounding the source 12 of the second transistor 10A in high frequency is provided. However, the present invention is not limited to this, and only one of the capacitors 18 and 19 may be provided. Even in this case, at least the leakage of the RF signal and the LO signal at the drain 15 output of the second transistor 10A is improved. Therefore, the same advantages as in the case of the present embodiment described above can be obtained.

Further, in the frequency conversion circuit of this embodiment, as the transistor, a single gate F is used as shown in FIG.
Although the ET is used, the present invention is not limited to this. For example, a bipolar transistor may be used for the first transistor and the second transistor, and even in this case, the same advantages as those of the above-described embodiment can be obtained. be able to. In this case, as shown in FIG. 3, the frequency conversion circuit using bipolar transistors as the first transistor 3B and the second transistor 10B receives the high frequency input signal at the emitter 1B and the local oscillation signal at the base 2B, as shown in FIG.
The first transistor 3B for frequency conversion which outputs the intermediate frequency signal from the collector 4B, and the first
A second transistor 10B for signal amplification, which is connected in tandem with the transistor 3B and amplifies and outputs the intermediate frequency signal.
And the base 2B of the first transistor 3B
Is applied with a voltage via the resistor 5, the emitter 1B of the first transistor 3B is grounded via the inductor 7, and the collector 4B of the first transistor 3B and the base 9B of the second transistor 10B. Is connected via a capacitor 8 and the collector 4B of the first transistor 3B and the emitter 12B of the second transistor 10B are connected via an inductor 11 which is open to an intermediate frequency signal. The voltage is applied to the base 9B of the two-transistor 10B via the resistor 13, and the voltage is applied to the collector 15B of the second transistor 10B via the inductor 16.

(B) Description of Second Embodiment FIG. 4 is an electric circuit diagram showing a frequency conversion circuit according to a second embodiment of the present invention. The frequency conversion circuit shown in FIG. 4 has a high frequency input signal (RF). Signal) and local oscillation signal (LO
Signal) and an intermediate frequency signal (IF signal)
In the frequency conversion circuit according to the present embodiment, the down converter 1 in FIG.
It can be used as 12 mixing circuits 112A.

Here, 22A is a first transistor, and this first transistor 22A receives an RF signal at the source 20 and an LO signal at the gate 21, thereby mixing the RF signal and the LO signal. The frequency is converted and the IF signal is output from the drain 23. That is, in the first transistor 22A,
Since the RF signal is input to the source 20, the LO signal is input to the gate 21, and the IF signal is output from the drain 23, there is no increase in the number of components for configuring the circuit, The isolation and large signal characteristics are improved.

In addition, the gate 2 of the first transistor 22A
1 is grounded via a resistor 24, and the source 20 is grounded via a resistor 25.
Both 25 are for one power supply. That is, the resistor 24 has a characteristic of being open to the LO signal, which prevents leakage of the LO signal input to the gate 21 and prevents signals having frequency components other than the LO band from being grounded. The discharge is prevented from being input to the gate 21, and the LO signal is matched. Further, the resistor 25 not only biases the source 20 of the first transistor 22A to obtain a predetermined operating point, but also has a characteristic of being open to an RF signal. The leakage of the RF signal input to the source 20 is prevented, and a signal having a frequency component other than the RF band is prevented from being ground-discharged and input to the source 20, thereby matching the RF signal.

Further, the drain 23 of the first transistor 22A is the gate 2 of the second transistor 29A described later.
6 is directly connected to the second transistor 29A
Is connected to the source 28 via a resistor 27. The second transistor 29A is connected in tandem with the first transistor 22A, and amplifies and outputs the IF signal from the first transistor 22A.

Here, the resistor 27 is the second transistor 2
It is a high resistance for biasing the source 28 of 9 A to obtain a predetermined operating point, and has a characteristic of hardly passing an IF signal. As a result, the IF signal output from the first transistor 22A is input to the gate 26 of the second transistor 29A without leaking to the source 28 of the second transistor 29A.

That is, the resistance 27 prevents the IF signal from leaking to the other place from the first transistor 22A, and the intermediate frequency signal leakage prevention circuit 70 for supplying the IF signal to the gate 26 of the second transistor 29A is constructed. To be done.
A power source 32 is connected to the drain 30 of the second transistor 29A via an inductor 31, and a voltage is applied to the drain 30 by the power source 32. Further, the inductor 31 has a characteristic that it is open to the IF signal, so that leakage of the amplified IF signal output to the drain 30 of the second transistor 29A to the power supply 32 is prevented. In addition to preventing this, the IF signal is matched.

By the way, the gate 26 of the second transistor 29A is grounded at a high frequency by the capacitor 33, which allows the drain 2 of the first transistor 22A to be grounded.
RF signal and LO signal leaked to 3 are discharged to earth,
The RF signal and the LO signal are prevented from being input to the gate 26 of the second transistor 29A, and the amplification characteristic of the IF signal is improved.

Further, the source 28 of the second transistor 29A is grounded at a high frequency by the capacitor 34, so that the RF and LO signals leaked to the drain 23 of the first transistor 22A are grounded like the capacitor 33 described above. Discharge, RF signal and LO signal are second
It prevents the input to the source 28 of the transistor 29A and enhances the amplification characteristic of the IF.

The above-mentioned grounded capacitor 33,
Reference numeral 34 is provided to increase reliability, and when designing the circuit, these can be omitted depending on the required circuit performance. With the configuration described above, the frequency conversion circuit according to the second embodiment of the present invention operates as follows.

That is, with the second transistor 29A, the power source 3
When a voltage is applied to the drain 30 by 2 and an RF signal is input to the source 20 of the first transistor 22A and an LO signal is input to the gate 21, the first transistor 22A mixes the RF signal and the LO signal. Then, the IF signal is output from the drain 23. The IF signal output from the drain 23 is input to the gate 26 by the intermediate frequency signal leakage prevention circuit 70 without leaking to the source 28 of the second transistor 29A, and the second transistor 29A amplifies the IF signal and is amplified. IF
The signal is output from the drain 30.

In the structure shown in FIG. 4 as well, similar to the case of FIG. 2 described above, a characteristic having a high input intercept point [IIP] can be obtained and the third-order distortion intermodulation distortion characteristic can be improved. , It is possible to prevent noise from being generated in adjacent channels. Further, in the first transistor 22A, the conversion gain of the IF signal is lowered due to the improvement of the third-order distortion cross-modulation distortion characteristic, but the conversion gain is lowered by the second transistor 29A.
Since the F signal is amplified efficiently, the gain reduction in the first transistor 22A is absorbed, and the reduction in conversion gain in the entire circuit is prevented, which allows the frequency conversion circuit with high output and low distortion to be realized. Has been realized.

As described above, according to the frequency conversion circuit of the second embodiment of the present invention, the first transistor 2 for frequency conversion is used.
2A and a second transistor 29A for signal amplification, the gate 21 of the first transistor 22A is grounded via the resistor 24, and the source 20 of the first transistor 22A is connected via the resistor 25. Grounded,
Further, the drain 23 of the first transistor 22A and the gate 26 of the second transistor 29A are directly connected, and the drain 23 of the first transistor 22A and the source 28 of the second transistor 29A are connected via a resistor 27, Further, the drain 30 of the second transistor 29A
By applying a voltage to the second transistor through the inductor 31, the leakage of the RF signal and LO signal from the first transistor 22A to the second transistor 29A can be prevented, and the IF signal from the first transistor 22A can be prevented. By the action of the intermediate frequency signal leakage prevention circuit 70, since it can be supplied to the gate 26 of the second transistor 29A without being leaked to another place and the IF signal can be matched, high output and low distortion can be obtained. It is possible to have the following circuit characteristics.

Further, according to the frequency conversion circuit of the present embodiment, the source 28 of the second transistor 29A is provided with the capacitor 34 grounded at high frequency, and the gate 26 of the second transistor 29A is grounded at high frequency with the capacitor 33. By providing the first transistor 22A
RF and LO signals leaked to the drain 23 of
It is possible to effectively prevent the input to the gate 26 of the second transistor 29A, improve the leakage of the RF signal and the LO signal to the drain 30 as an IF port, and further improve the amplification characteristic of the second transistor 29A. Therefore, the number of elements of the matching circuit in the drain 30 of the second transistor 29A can be reduced, and there is an advantage that it is possible to realize a frequency conversion circuit having higher output and lower distortion while being small in size.

Further, according to the frequency conversion circuit of this embodiment, the RF signal is input to the source 20 of the first transistor 22A, the LO signal is input to the gate 21, and the IF signal is output from the drain 23. It is possible to improve the large signal characteristic as well as the isolation between the RF signal and the LO signal without increasing the number of parts constituting the circuit.

In the present embodiment described above, the capacitor 33 for grounding the gate 26 of the second transistor 29A at a high frequency is provided, and the second transistor 29A is also provided.
Is provided with a capacitor 34 for grounding the source 28 of the above in a high frequency, but the present invention is not limited to this, and only one of the capacitors 33 and 34 may be provided,
Even in this way, at least the second transistor 29
Since the leakage of the RF signal and the LO signal to the drain 30 of A can be improved, the same advantages as in the case of this embodiment described above can be obtained.

Further, in the frequency conversion circuit of this embodiment, a single gate F is used as a transistor as shown in FIG.
Although the ET is used, the present invention is not limited to this. For example, a bipolar transistor may be used for the first transistor and the second transistor, and even in this case, the same advantages as those of the above-described embodiment can be obtained. be able to. In this case, in particular, the frequency conversion circuit using bipolar transistors for the first transistor 22B and the second transistor 29B receives a high frequency input signal at the emitter 20B and a local oscillation signal at the base 21B as shown in FIG. By receiving the intermediate frequency signal, the collector 2
First transistor 22 for frequency conversion output from 3B
B and a second transistor 29B for signal amplification which is tandem-connected to the first transistor 22B and amplifies and outputs the intermediate frequency signal, and the first transistor 22
The base 21B of B is grounded via the resistor 24, and the emitter 20B of the first transistor 22B is grounded via the resistor 25.
The collector 23B of 2B and the base 26B of the second transistor 29B are directly connected, and the collector 23B of the first transistor 22B and the second transistor 29B are connected.
Is connected to the emitter 28B of the second transistor 29B via the resistor 27, and a voltage is applied to the collector 30B of the second transistor 29B via the inductor 31.

(C) Description of Third Embodiment FIG. 6 is an electric circuit diagram showing a frequency conversion circuit according to a third embodiment of the present invention. The frequency conversion circuit shown in FIG. 6 has a high frequency input signal (RF). Signal) and local oscillation signal (LO
Signal) and an intermediate frequency signal (IF signal)
In the frequency conversion circuit according to the present embodiment, the down converter 1 in FIG.
It can be used as 12 mixing circuits 112A.

Here, 37A is a first transistor, and the first transistor 37A receives the RF signal at the source 35 via the matching circuit 50 and the LO signal at the gate 36 via the inductor 56. As a result, the RF signal and the LO signal are mixed, the frequency is converted, and the IF signal is output from the drain 38.

That is, in the first transistor 37A, the RF signal is input to the source 35 via the matching circuit 50, while the LO signal is input to the gate 36 via the inductor 56, and the IF signal is output from the drain 38. Since the signal is output, the isolation between the RF signal and the LO signal and the large signal characteristic are improved without increasing the number of components for forming the circuit.

Here, the matching circuit 50 is for matching the RF signal, and includes a capacitor 50A, an inductor 50B and a capacitor 50C. The gate 36 of the first transistor 37A is grounded via the resistor 39, the source 35 is grounded via the inductor 40 and the resistor 41, and is also grounded via the inductor 40 and the capacitor 51. It should be noted that these resistors 39 and 41 are both for one power supply.

Further, the resistor 39 has a characteristic of being open to the LO signal, which prevents the LO signal input to the gate 36 from leaking and at the same time L
A signal having a frequency component other than the O band is prevented from being input to the gate 36, and the LO signal is matched. Further, the inductor 40 has a characteristic that it is open to the RF signal, and the resistor 41 is biased to obtain a predetermined operating point and is open to the RF signal. These characteristics prevent leakage of the RF signal input to the source 35, and prevent signals having frequency components other than the RF band from being ground-discharged and input to the source 35. It is designed to match signals.

The source 3 of the first transistor 37A
The connection point between the inductor 40 and the resistor 41, which is connected to 5, is grounded via the capacitor 51.
The current to the first transistor 37A is increased to increase the conversion gain of the first transistor 37A. Further, the drain 38 of the first transistor 37A is directly connected to the gate 42 of the second transistor 46A described later and is also connected to the source 45 of the second transistor 46A via the inductor 43 and the resistor 44.

46A is a second transistor,
The second transistor 46A is the first transistor 37.
It is connected in tandem with A and amplifies and outputs the IF signal from the first transistor 37A. Here, the inductor 43 has a characteristic that it is open with respect to the IF signal, whereby the first transistor 37A
The IF signal output from the second transistor 46A does not leak to the source 45 of the second transistor 46A.
It is input to the gate 42 of A.

The resistor 44 is the second transistor 46.
It is a high resistance for biasing the source 45 of A in order to obtain a predetermined operating point, and has a characteristic of allowing the IF signal to pass only slightly. As a result, the IF signal output from the first transistor 37A is input to the gate 42 of the second transistor 46A without leaking to the source 45 of the second transistor 46A.

That is, the IF signal is transmitted to the second transistor 4 while preventing the leakage of the IF signal from the first transistor 37A to another place by the inductor 43 and the resistor 44.
An intermediate frequency signal leakage prevention circuit 80 for supplying to the gate 42 of 6A is configured. A power source 49 is connected to the drain 47 of the second transistor 46A via an inductor 48, and a voltage from the power source 49 is applied to the drain 47. Further, the inductor 48 has a characteristic of being open to the IF signal, whereby the power supply 4 for the IF signal output to the drain 47 of the second transistor 46A and amplified.
The IF signal is adapted to be matched while preventing leakage to the signal line 9.

By the way, the matching circuit 50 is connected to the source 35 of the first transistor 37A, so that the RF signal inputted to the source 35 of the first transistor 37A is matched. Furthermore, the second
The gate 42 of the transistor 46A is grounded at a high frequency by the capacitor 52, whereby the RF signal and the LO signal leaked to the drain 38 of the first transistor 37A are discharged to the ground, and the RF signal and the LO signal are discharged to the second transistor 46A. It is prevented from being input to the gate 42 and the amplification characteristic of the IF signal is enhanced.

Further, the source 4 of the second transistor 46A
Reference numeral 5 is grounded via the resistor 53, thereby increasing the conversion gain of the second transistor 46A. Further, the source 45 of the second transistor 46A is grounded at a high frequency by the capacitor 54, so that the RF and LO signals leaked to the drain 38 of the first transistor 37A are ground-discharged like the capacitor 52 described above. The RF and LO signals are prevented from being input to the source 45 of the second transistor 46A, and the IF amplification characteristic is improved.

Further, the drain 47 of the second transistor 46A is grounded at a high frequency by the capacitor 55, which allows the drain 4 of the second transistor 46A to be grounded.
The RF and LO signals leaked to 7 are discharged to earth and IF
Improves signal amplification characteristics. The matching circuit 5 described above
0, capacitors 51, 52, 54, 55, and resistor 53 are
It is provided to increase reliability, and these can be omitted in the circuit design depending on the required circuit performance.

With the above structure, the frequency conversion circuit according to the third embodiment of the present invention operates as follows.
That is, in the second transistor 46A, a voltage is applied to the drain 47 from the power supply 49, and at the same time, the source 35 of the first transistor 37A is supplied with R via the matching circuit 50.
When the LO signal is input to the gate 36 via the inductor 56 while the F signal is input, the first transistor 3
7A mixes the RF signal and the LO signal and outputs the IF signal from the drain 38.

The IF signal output from the drain 38 is
It is input to the gate 42 by the intermediate frequency signal leakage prevention circuit 80 without leaking to the source 45 of the second transistor 46A. The second transistor 46A amplifies the IF signal, and the amplified IF signal is output from the drain 47. In addition, also in the one shown in FIG.
, The high input intercept point [I
IP] can be obtained, the third-order distortion intermodulation distortion characteristics can be improved, and noise can be prevented from occurring in adjacent channels.

In addition, in the first transistor 37A, the conversion gain of the IF signal decreases as the third-order distortion cross-modulation distortion characteristic is improved, but the second transistor 46A converts the IF signal whose conversion gain decreases. Since the gain can be efficiently amplified, the gain reduction in the first transistor 37A can be absorbed, and the reduction in the conversion gain of the entire circuit can be prevented, thereby realizing a high-output and low-distortion frequency conversion circuit. is doing.

As described above, according to the frequency conversion circuit of the third embodiment of the present invention, it is provided with the first transistor 37A and the second transistor 46A, and the gate 36 of the first transistor 37A is grounded via the resistor 39. As well as
The source 35 of the first transistor 37A has an inductor 40 and a resistor 4 which are open to a high frequency input signal.
1 is grounded through the first transistor 37A
Drain 38 and the gate 42 of the second transistor 46A
Are directly connected to each other, and the first transistor 37
The drain 38 of A and the source 4 of the second transistor 46A
5 is connected via an inductor 43 and a resistor 44 that are open to an intermediate frequency signal, and a voltage is applied to the drain 47 of the second transistor 46A via the inductor 48, so that Second transistor 4 for RF signal and LO signal from transistor 37A
6A can be prevented from leaking, and the IF signal from the first transistor 37A can be supplied to the gate 42 of the second transistor 46A by the intermediate frequency signal leakage prevention circuit 80 without being leaked to another place. At the same time, since the IF signal can be matched, there is an advantage that the circuit characteristics of high output and low distortion can be obtained.

Further, according to the frequency conversion circuit of this embodiment, the source 45 of the second transistor 46A is provided with the capacitor 54 grounded in high frequency, and the gate 42 of the second transistor 46A is grounded in high frequency with the capacitor 52. By providing the first transistor 37A
RF signal and LO signal leaked to the drain 38 of
The input to the gate 42 of the second transistor 46A can be effectively prevented, the leakage of the RF signal and the LO signal to the drain 47 as an IF port can be improved, and the amplification characteristic of the second transistor 46A can be further improved. Therefore, the number of elements of the matching circuit in the drain 47 of the second transistor 46A can be reduced, and there is an advantage that it is possible to realize a frequency conversion circuit having higher output and lower distortion while being compact.

According to the frequency conversion circuit of this embodiment, the RF signal is input to the source 35 of the first transistor 37A, the LO signal is input to the gate 36, and the IF signal is output from the drain 38. It is possible to improve the large signal characteristic as well as the isolation between the RF signal and the LO signal without increasing the number of parts constituting the circuit.

In this embodiment described above, the capacitor 52 for grounding the gate 42 of the second transistor 46A at high frequency is provided, and the second transistor 46A is also provided.
Is provided with the capacitor 54 for grounding the source 45 of the above in a high frequency, but the present invention is not limited to this, and only one of the capacitor 52 and the capacitor 54 may be provided,
Even in this case, at least the second transistor 46
Since the leakage of the RF signal and the LO signal to the drain 47 of A can be improved, the same advantages as in the case of this embodiment described above can be obtained.

Further, in the frequency conversion circuit of this embodiment, as the transistor, as shown in FIG.
Although the ET is used, the present invention is not limited to this. For example, a bipolar transistor may be used for the first transistor and the second transistor, and even in this case, the same advantages as those of the above-described embodiment can be obtained. be able to. In this case, the frequency conversion circuit using bipolar transistors as the first transistor 37B and the second transistor 46B receives a high frequency input signal at the emitter 35B and a local oscillation signal at the base 36B, as shown in FIG. By receiving the intermediate frequency signal, the collector 3
First transistor 37 for frequency conversion output from 8B
B, and a second transistor 46B for signal amplification which is connected in tandem with the first transistor 37B and amplifies and outputs the intermediate frequency signal, and the first transistor 37
The B base 36B is grounded via the resistor 39, the first transistor 37B emitter 35B is grounded via the inductor 40 and the resistor 41 which are open to the high frequency input signal, and the first transistor 37B is further grounded. Is directly connected to the collector 38B of the second transistor 46B and the collector 38B of the second transistor 46B.
B emitter 45B is connected through an inductor 43 and a resistor 44 that are open to an intermediate frequency signal,
Furthermore, a voltage is applied to the collector 47B of the second transistor 46B via the inductor 48.

[0092]

As described above in detail, according to the frequency conversion circuit of the present invention of claim 1, wherein: a first transistor for frequency conversion, and a second transistor for signal amplification, a second
Get a predetermined operating point at the gate or base of a transistor
To bias the capacitor and the intermediate frequency signal
And an inductor that has characteristics that it becomes open
And a drain or collector of the first transistor is connected to the intermediate frequency signal leakage prevention circuit.
Source or emitter of the second transistor via the ductor
Is connected to the drain of the first transistor or
Is the collector of the second transistor via the capacitor.
It is possible to prevent the RF signal and the LO signal from the first transistor from leaking to the second transistor, and the IF signal from the first transistor leaks to another place by being connected to the base or the base. Second without being
Since it can be supplied to the gate or base of the transistor and the IF signal can be matched, there is an advantage that the circuit characteristics can be high output and low distortion.

According to a second aspect of the frequency conversion circuit of the present invention, the frequency conversion circuit includes a first transistor for frequency conversion and a second transistor for signal amplification. A voltage is applied to the base via a resistor, the source or emitter of the first transistor is grounded via an inductor, and the drain or collector of the first transistor and the gate of the second transistor are further connected. Alternatively, the base is connected via a capacitor, and the drain or collector of the first transistor and the source or emitter of the second transistor are connected via an inductor that is open to an intermediate frequency signal, Furthermore, when a voltage is applied to the above-mentioned gate or base of the second transistor via a resistor, , To the drain or collector of the second transistor, a voltage is applied via the inductor, RF signal from the first transistor, L
The O signal can be prevented from leaking to the second transistor, and the IF signal from the first transistor can be supplied to the gate or the base of the second transistor without being leaked to another place, and the IF signal Since matching can be achieved, there is an advantage that the circuit characteristics of high output and low distortion can be obtained.

Further, according to the frequency conversion circuit of the present invention, the first transistor for frequency conversion and the second transistor for signal amplification are provided, and
The above-mentioned gate or base of the first transistor is grounded via a resistor, and the above-mentioned source or emitter of the first transistor is grounded via a resistor, and the above-mentioned drain or collector of the first transistor is further connected. And the gate or base of the second transistor are directly connected, and the drain or collector of the first transistor and the source or emitter of the second transistor are connected.
Predetermined operating point for the source or emitter of the second transistor
High resistance for biasing to gain
The RF signal from the first transistor is connected to the drain or collector of the second transistor through the inductor, which is connected through a resistor having a characteristic of hardly passing a frequency signal. , L
The O signal can be prevented from leaking to the second transistor, and the IF signal from the first transistor can be supplied to the gate or the base of the second transistor without being leaked to another place, and the IF signal Since matching can be achieved, there is an advantage that the circuit characteristics of high output and low distortion can be obtained.

According to a fourth aspect of the frequency conversion circuit of the present invention, the frequency conversion circuit includes a first transistor for frequency conversion and a second transistor for signal amplification. The base is grounded via a resistor, and the source or emitter of the first transistor is grounded via an inductor and a resistor that are open to a high frequency input signal. An inductor in which the drain or collector and the gate or base of the second transistor are directly connected, and the drain or collector of the first transistor and the source or emitter of the second transistor are open to an intermediate frequency signal; and Connected via a resistor, and further connected to the drain or collector of the second transistor A voltage is applied via the inductor, RF signal from the first transistor, LO
The signal can be prevented from leaking to the second transistor, and the IF signal from the first transistor can be supplied to the gate or the base of the second transistor without being leaked to another place, and the IF signal can be matched. Therefore, there is an advantage that the circuit characteristics of high output and low distortion can be obtained.

According to the frequency conversion circuit of the present invention as defined in claim 5, since the capacitor for grounding the source or the emitter of the second transistor in high frequency is provided, the drain or collector of the first transistor is provided. Effectively prevent the leaked RF signal and LO signal from being input to the gate or base of the second transistor,
Since the leakage of RF and LO signals from the drain or collector serving as the IF port can be improved and the amplification characteristic of the second transistor can be further improved, the number of matching circuit elements in the drain or collector of the second transistor can be reduced. It is possible to realize a frequency conversion circuit with higher output and lower distortion while being compact.

Further, according to the frequency conversion circuit of the present invention, the capacitor for grounding the gate or the base of the second transistor in high frequency is provided, so that the drain or collector of the first transistor is provided. Effectively prevent the leaked RF signal and LO signal from being input to the gate or base of the second transistor,
Since the leakage of RF and LO signals from the drain or collector serving as the IF port can be improved and the amplification characteristic of the second transistor can be further improved, the number of matching circuit elements in the drain or collector of the second transistor can be reduced. It is possible to realize a frequency conversion circuit with higher output and lower distortion while being compact.

According to a seventh aspect of the frequency conversion circuit of the present invention, a capacitor for grounding the source or emitter of the second transistor in high frequency is provided, and the gate or base of the second transistor is provided. By providing a capacitor for grounding the high frequency with high frequency, it is possible to effectively prevent the RF signal and the LO signal leaked to the drain or collector of the first transistor from being input to the gate or base of the second transistor. Signal or L of drain or collector as
Since the leakage of the O signal can be improved and the amplification characteristic of the second transistor can be further improved, the number of elements of the matching circuit in the drain or collector of the second transistor can be reduced, and the size can be further improved while being small. There is an advantage that a frequency conversion circuit with output and low distortion can be realized.

Further, according to the frequency conversion circuit of the present invention, the connection point between the inductor and the resistor connected to the source or the emitter of the first transistor is connected via the capacitor. By being grounded,
The current to the first transistor can be increased, the conversion gain of the first transistor can be increased, and the source or the emitter of the second transistor is grounded via another resistor, so that Since the current can be increased and the conversion gain of the second transistor can be increased, there is an advantage that a frequency conversion circuit with higher output and lower distortion can be realized.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram showing a frequency conversion circuit according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a result of soft simulation about a third-order distortion cross-modulation distortion characteristic performed by using the frequency conversion circuit according to the first embodiment of the present invention.

FIG. 3 is an electric circuit diagram showing a frequency conversion circuit according to a modification of the first embodiment of the present invention.

FIG. 4 is an electric circuit diagram showing a frequency conversion circuit according to a second embodiment of the present invention.

FIG. 5 is an electric circuit diagram showing a frequency conversion circuit according to a modification of the second embodiment of the present invention.

FIG. 6 is an electric circuit diagram showing a frequency conversion circuit according to a third embodiment of the present invention.

FIG. 7 is an electric circuit diagram showing a frequency conversion circuit according to a modification of the third embodiment of the present invention.

FIG. 8 is a block diagram for explaining the configuration of a general wireless device.

FIG. 9 is a diagram showing a configuration of a frequency conversion circuit using a dual gate FET.

FIG. 10 is a diagram showing a configuration of a frequency conversion circuit using a bipolar transistor.

FIG. 11 is a diagram showing a configuration of a frequency conversion circuit using a single gate FET.

[Explanation of symbols]

1 source 1B emitter 2 gates 2B base 3A, 3B first transistor 4 drain 4B collector 5 resistance 6 power supply 7 inductor 8 capacitors 9 gates 9B base 10A, 10B Second transistor 11 inductor 12 sources 12B emitter 13 resistance 14 power supply 15 drain 15B collector 16 inductor 17 power supply 18, 19 capacitors 60 Intermediate frequency leakage prevention circuit 20 sources 20B emitter 21 gate 21B base 22A, 22B First transistor 23 drain 23B collector 24, 25 resistance 26 gates 26B base 27 Resistance 28 sources 28B emitter 29A, 29B Second transistor 30 drain 30B collector 31 Inductor 32 power supplies 33, 34 capacitors 70 Intermediate frequency leakage prevention circuit 35 sources 35B emitter 36 gates 36B base 37A, 37B First transistor 38 drain 38B collector 39 Resistance 40 inductor 41 Resistance 42 gates 42B base 43 inductor 44 Resistance 45 source 45B emitter 46A, 46B Second transistor 47 drain 47B collector 48 inductor 49 power supply 50 matching circuit 50A capacitor 50B inductor 50C capacitor 51, 52 capacitors 53 resistance 54, 55 capacitors 56 inductor 80 Intermediate frequency leakage prevention circuit 100 high frequency transmitter 101 Modulator 102 up-converter 102A mixing circuit 102B Voltage controlled oscillator (VCO) 103 amplifier 104 duplexer 105 antenna 110 high frequency receiver 111 Low Noise Amplifier (LNA) 112 down converter 112A mixing circuit (frequency conversion circuit) 112B Voltage controlled oscillator (VCO) 113 amplifier 114 demodulator 200 frequency conversion circuit 201 first gate 202 second gate 203 Source 204 Dual gate FET 205 drain 206 matching circuit 206A capacitor 206B inductor 206C capacitor 207 Matching circuit 207A capacitor 207B inductor 207C capacitor 208 resistance 209 capacitor 210, 211 resistance 212 inductor 213 capacitor 214 power supply 215 Matching circuit 215A capacitor 215B inductor 215C capacitor 215D capacitor 300 frequency conversion circuit 301 Composite point 302 base 303 Emitter 304 bipolar transistor 305 collector 306 Matching circuit 307 Transmission line 308 Matching circuit 309 Transmission line 310 resistance 311 Capacitor 312 resistance 313 power supply 314 Capacitor 315 inductor 316 resistance 317 Matching circuit 317A capacitor 317B inductor 317C capacitor 317D capacitor 400 frequency conversion circuit 401 source 402 gate 403 Single gate FET 404 drain 405 filter

Continuation of front page (58) Fields investigated (Int.Cl. ⁷ , DB name) H03D 7/12

Claims (9)

(57) [Claims] 1. A frequency conversion circuit for mixing a high frequency input signal and a local oscillation signal to output an intermediate frequency signal, wherein the high frequency input signal is received by a source or an emitter and the local oscillation signal is received by a gate or a base. A first transistor for frequency conversion that outputs the intermediate frequency signal from the drain or the collector, and a second transistor for signal amplification that is tandem connected to the first transistor and that amplifies and outputs the intermediate frequency signal. And providing the intermediate frequency signal to the gate or the base of the second transistor while preventing leakage of the intermediate frequency signal from the first transistor to another place .
To get the desired operating point to the gate or base of the
A capacitor that applies astigmatism and an offset for the intermediate frequency signal
An inductor with characteristics that makes it open
Is equipped with an intermediate frequency signal leakage prevention circuit comprising a drain or collector of said first transistor, said in
The source or emitter of the second transistor is connected through the inductor.
Connected to the drain of the first transistor
The second transistor is connected to the second transistor via the capacitor.
A frequency conversion circuit configured to be connected to the gate or the base of the star . 2. A frequency conversion circuit which mixes a high frequency input signal and a local oscillation signal and outputs an intermediate frequency signal, wherein the high frequency input signal is received by a source or an emitter and the local oscillation signal is received by a gate or a base. A first transistor for frequency conversion that outputs the intermediate frequency signal from the drain or the collector, and a second transistor for signal amplification that is tandem connected to the first transistor and that amplifies and outputs the intermediate frequency signal. A voltage is applied to the gate or base of the first transistor via a resistor, and the source or emitter of the first transistor is grounded via an inductor; and The drain or collector of the first transistor and the gate or base of the second transistor are The drain or collector of the first transistor and the source or emitter of the second transistor are connected via an inductor that is open to the intermediate frequency signal, and A voltage is applied to the gate or the base of the second transistor via a resistor, and a voltage is applied to the drain or the collector of the second transistor via an inductor. , Frequency conversion circuit. 3. A frequency conversion circuit which mixes a high frequency input signal and a local oscillation signal and outputs an intermediate frequency signal, wherein the high frequency input signal is received by a source or an emitter and the local oscillation signal is received by a gate or a base. A first transistor for frequency conversion that outputs the intermediate frequency signal from the drain or the collector, and a second transistor for signal amplification that is tandem connected to the first transistor and that amplifies and outputs the intermediate frequency signal. And the gate or base of the first transistor is grounded via a resistor, and the source or emitter of the first transistor is grounded via a resistor. The drain or collector of the transistor and the gate or base of the second transistor are directly connected. Rutotomoni, the source or emitter of the drain or collector and the second transistor of the first transistor, the source or emitter of the second transistor
High to bias to get the desired operating point
It is a resistor and is a special resistor that hardly passes the intermediate frequency signal.
A frequency conversion circuit, characterized in that the voltage is applied to the drain or collector of the second transistor through an inductor, the voltage being applied to the drain or collector of the second transistor. 4. A frequency conversion circuit for mixing a high frequency input signal and a local oscillation signal to output an intermediate frequency signal, wherein the high frequency input signal is received by a source or an emitter and the local oscillation signal is received by a gate or a base. A first transistor for frequency conversion that outputs the intermediate frequency signal from the drain or the collector, and a second transistor for signal amplification that is tandem connected to the first transistor and that amplifies and outputs the intermediate frequency signal. And an inductor and a resistor in which the gate or base of the first transistor is grounded via a resistor and the source or emitter of the first transistor is open to the high frequency input signal. Grounded through the drain or collector of the first transistor. An inductor in which the gate or base of the second transistor is directly connected, and the drain or collector of the first transistor and the source or emitter of the second transistor are open to the intermediate frequency signal; A frequency conversion circuit, wherein the frequency conversion circuit is connected via a resistor, and a voltage is applied to the drain or collector of the second transistor via an inductor. 5. any one of claims 2 to 4, characterized in that capacitor to ground the source or emitter of the second transistor a high frequency is provided
The frequency conversion circuit according to item . Wherein wherein the gate or the base of the second transistor in any one <br/> of claims 2 to 4, characterized in that the capacitor grounding high frequency manner is provided Frequency conversion circuit. 7. A capacitor for grounding the source or emitter of the second transistor in a high frequency manner is provided, and a capacitor for grounding the gate or base of the second transistor in a high frequency manner is provided. frequency converter according to any one of claims 2 to 4, characterized in. 8. The frequency converter according to claim 4, wherein a connection point between the inductor and the resistor connected to the source or the emitter of the first transistor is grounded via a capacitor. circuit. 9. The frequency conversion circuit according to claim 4, wherein the source or the emitter of the second transistor is grounded via another resistor.