JP2000059146A - Mixer circuit and receiving circuit - Google Patents

Abstract

(57) [Summary] [Problem] To suppress the deterioration of the NF characteristic or the like by suppressing the leakage of the local oscillation signal input to the mixer to the RF signal input side.
Deterioration of secondary distortion characteristics is reduced. An RF buffer transistor is provided.
By connecting the series connection point of the NF and the distortion improvement capacitors 114 and 115 between the drains, leakage of the local oscillation signal to the RF signal input side is suppressed, and the deterioration of the NF characteristic and the deterioration of the secondary distortion characteristic are reduced. did.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver for TV, cable television (CATV), satellite broadcasting, satellite communication, cellular telephone, and the like, and a mixer circuit for high-frequency signal processing used in the receiver.

[0002]

2. Description of the Related Art FIG. 5 shows an example of an upconverter section of a CATV tuner of a double super system as a conventional example of a mixer circuit.

The mixer circuit shown in FIG.
F signal (radio frequency signal) input terminals 101 and 102, intermediate frequency output terminal 108, local oscillation signal input terminal 127,
128 and an output transformer 109. further,
The mixer circuit shown is a frequency conversion transistor 110, 1
11, 112, 113 and RF buffer transistor 11
6, 117, a current source transistor 120, a variation absorption resistor 121, and bleeder resistors 104, 105, 12
3, 124, and bias application resistors 106, 107, 12
5 and 126 and a high-frequency grounding capacitor 122.

The output winding of a transformer 109 shown in FIG. 1 is connected to an intermediate frequency output terminal 108, and the power supply winding has an intermediate tap grounded at a high frequency by a grounding capacitor 122. To one input are the drain of the frequency conversion transistor 110 and the frequency conversion transistor 11.
2 is connected to the second input terminal to output a first intermediate frequency signal. The other input of the power supply side winding is connected to the drain of the frequency conversion transistor 111 and the frequency conversion transistor 11.
3 are connected to each other to output a second intermediate frequency signal. The first and second intermediate frequency signals are combined and output from the output winding. The power supply voltage is supplied from the power supply terminal 103 via an intermediate tap of the power supply side winding.

The frequency conversion transistor 110
And 111 and the sources of the frequency conversion transistors 112 and 113 are commonly connected to each other.
Connected to the drains of buffer transistors 116 and 117 and RF buffer transistors 116 and 1
The NF and the strain improvement capacitor 501 are connected between the drains of the drain 17. Also, the RF buffer transistors 116 and 117
Are connected to the drain of the current source transistor 120 via the distortion improving resistors 118 and 119, respectively. The gate of the current source transistor 120 is directly grounded, and the source is grounded by the variation absorbing resistor 121.

The gates of the frequency conversion transistors 110 and 113 and the frequency conversion transistors 111 and 1
Twelve gates are commonly connected, their common connection points are connected to local oscillation signal input terminals 127 and 128, respectively, and voltages divided by bleeder resistors 123 and 124 are applied via bias application resistors 125 and 126. These are applied to the local oscillation signal input terminals 127 and 128, respectively. Further, the RF buffer transistors 116 and 11
7 are RF signal input terminals 101 and 102, respectively.
And the voltages divided by the bleeder resistors 104 and 105 are applied to the bias application resistors 10 and 10, respectively.
6, 107.

[0007] The above mixer circuit has an RF signal input terminal 10.
After amplifying the RF signal inputted between the RF transistors 1 and 102 by the RF buffer transistors 116 and 117, the frequency conversion transistors 110, 111, 112 and 113
The frequency of the local oscillation signal input between the local oscillation signal input terminals 127 and 128 is converted into an intermediate frequency signal and output to the intermediate frequency output terminal 108.

Further, in the mixer circuit shown in FIG.
No. 75810, the frequency conversion transistors 110, 111, 112, 11
When the local oscillation signal input to the gate of No. 3 leaks to the drain side of the RF buffer transistors 116 and 117,
Since the leaked local oscillation signal hinders the frequency conversion operation, there is a problem that a noise figure (NF) characteristic and a distortion characteristic of the mixer are deteriorated.

For this reason, in the prior art shown in FIG.
Similarly to the mixer circuit described in No. 5810, by adding a capacitor 501 between the drains of the RF buffer transistors 116 and 117 that can be ignored for the RF signal frequency and has low impedance for the local oscillation signal frequency. RF buffer transistor 116 for local oscillation signal,
The NF characteristics and the distortion characteristics are improved by suppressing the leakage of 117 to the drain side. Further, the distortion improvement resistor 11 is connected between the sources of the RF buffer transistors 116 and 117.
The distortion characteristics are also improved by inserting 8,119 and applying feedback.

[0010]

In the mixer circuit shown in the prior art, the RF buffer transistors 116, 11
7, a NF and a distortion improvement capacitor 501 are added between the drains of the RF buffer transistors 1 for local oscillation signals.
The NF characteristics and the distortion characteristics are improved by suppressing the leakage of the RF buffer transistors 116 and 117 to the drain side. However, when the local oscillation signal components having the same phase leak into both the drains of the RF buffer transistors 116 and 117, respectively. Has an RF
Even if a capacitor is inserted between the drains of the buffer transistors, the high frequency current of the local oscillation signal component does not flow, so that it is impossible to suppress the leakage of the RF buffer transistors to the drain side.

For this reason, when a local oscillation signal component having the same phase leaks, the local oscillation signal leaks to the RF buffer side to a large extent, so that there has been a problem that NF characteristics and distortion characteristics deteriorate. Regarding the third-order distortion characteristic among the distortion characteristics, the mixer current is increased and the gate sizes of the frequency conversion transistors 110, 111, 112, 113 and the RF buffer transistors 116, 117 are appropriately selected with respect to the mixer current. Can be improved.

However, the secondary distortion characteristics can be improved by increasing the resistance of the distortion improvement resistors 118 and 119 inserted between the sources of the RF buffer transistors 116 and 117 and increasing the feedback amount. In addition, there has been a problem that conversion gain and NF characteristics are deteriorated.

An object of the present invention is to solve the above problem and to suppress the leakage of the local oscillation signal to the RF buffer side (RF signal input side), thereby providing a mixer circuit with less deterioration of the NF characteristic and the secondary distortion characteristic. To provide.

[0014]

A first means for solving the above-mentioned problem is that the capacitor is not simply inserted between the drains of the RF buffer transistors of the mixer circuit.
A series body of first and second capacitors having the same capacitance is inserted between the drains of the buffer transistors, and the first and second capacitors have the same capacitance.
The connection point of the capacitor is grounded.

With the above configuration, if local oscillation signal components having opposite phases and equal amplitudes leak into the drains of the RF buffer transistors 116 and 117, respectively,
Since it can be regarded as equivalent to a case where a capacitance is simply inserted between the drains of the RF buffer transistors as in the conventional example shown in FIG. 5, the first and second capacitance values are twice the capacitance value of the conventional example in FIG. Then, the NF characteristics and the second-order distortion characteristics can obtain substantially the same performance as the conventional example of FIG.

The RF buffer transistor 116,
When the local oscillation signal component having the same phase leaks into both the drains of the RF transistor 117, both the drains of the RF buffer transistor can be ignored for the RF signal frequency, and have a low impedance for the local oscillation signal frequency. Since the first and second capacitors are grounded,
Leakage of the local oscillation signal to the drain side of the RF buffer transistor can be suppressed.

As described above, by inserting a series body of capacitors between both drains of the RF buffer transistor and grounding the connection point, leakage of the local oscillation signal to the drain side of the RF buffer transistor is achieved. However, since the phase can be suppressed even if the phases are the same or opposite to each other, it is possible to suppress the deterioration of the NF characteristic and the deterioration of the secondary distortion characteristic.

A second means for solving the above-mentioned problem is that one of the RF signal input terminals of the mixer circuit is grounded at a high frequency by using a high-frequency grounding capacitor to input an unbalanced signal. A series body of the first and second capacitors having the same capacitance is inserted between the drains of the RF buffer transistor, and the first capacitor is connected between the connection point of the first and second capacitors and the RF signal input terminal on the high-frequency ground side. The resistance is added.

With the above configuration, the first and the second
Is connected to the first resistor and the RF signal input terminal via a high-frequency grounding capacitor.
Since the leakage to both drain sides of the buffer transistor can be suppressed even if they are in phase or opposite to each other, N
It is possible to suppress the deterioration of the F characteristic and the deterioration of the secondary distortion characteristic. Further, if the amplified balanced RF signals output to the two drains of the RF buffer transistor have the same amplitude in opposite phases to each other, the RF signal component is connected to the connection point between the first and second capacitors. Does not occur.

However, if the RF buffer transistor is uneven or the RF input terminal is insufficiently grounded at a high frequency on the ground side, the RF signals output to both drains of the RF buffer transistor do not have the same amplitude and the balance is lost. Therefore, an unbalanced component of the RF signal occurs at the connection point between the first and second capacitors. In addition, this unbalanced RF
The signal is transmitted to the frequency conversion transistors 110, 111, 11
2, 113, the secondary distortion characteristics deteriorate.

On the other hand, since the grounding capacitance of the RF input terminal at the high frequency grounding contains a small inductor component, it has a slight impedance.
By connecting the connection point of the capacitance of the RF input terminal and the high-frequency ground terminal of the RF input terminal with a resistor, an unbalanced component of the RF signal output to both the drains of the RF buffer transistor is fed back, and both the drains of the RF buffer transistor are To improve the balance of the RF signal output to the device.

As described above, according to the second means for solving the above-mentioned problem, the local oscillation signal is prevented from leaking to the drain side of the RF buffer transistor, so that N
In addition to suppressing the deterioration of the F characteristic and the deterioration of the second-order distortion characteristic, the unbalanced component of the RF signal output to both drains of the RF buffer transistor is reduced by the small inductor component of the high-frequency ground capacitance of the RF input terminal. By using the feedback to improve the balance of the RF signal,
Frequency conversion transistors 110, 111, 112, 1
In 13, the secondary distortion characteristic deteriorated due to the imbalance of the RF signal can be improved.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing a first embodiment of a mixer circuit according to the present invention.
F, a distortion improvement capacity, the same reference numerals are given to portions corresponding to FIG. 5, and redundant description will be omitted.

In the figure, in the first embodiment, a series connection of NF and distortion improvement capacitors 114 and 115 is connected between the drains of RF buffer transistors 116 and 117, and NF and distortion improvement capacitance 114 are connected. The connection point between the NF and the distortion improvement capacitor 115 is grounded. The other configuration is the same as that of the conventional mixer circuit shown in FIG.
Also, as in the conventional mixer circuit shown in FIG. 5, the RF signal input between the RF signal input terminals 101 and 102 is amplified by the RF buffer transistors 116 and 117, and then the frequency conversion transistor 110 is operated. , 11
At 1, 112 and 113, the local oscillation signal input terminal 1
The frequency is converted into an intermediate frequency signal by the local oscillation signal input between 27 and 128 and output to the intermediate frequency output terminal 108.

In the first embodiment, the capacitance is not simply added between the drains of the RF buffer transistors 116 and 117 as in the conventional mixer circuit shown in FIG. By inserting a series body of capacitors between them and grounding the connection point, the leakage of the local oscillation signal to both the drain sides of the RF buffer transistor is not only when the phases are opposite to each other, but also when Even in the same phase, suppression is possible, so that deterioration of the NF characteristic and the second-order distortion characteristic can be suppressed even in the reception band where the leakage of the local oscillation signal is in the same phase. Further, the same effect can be obtained even if the active element used in the mixer circuit shown in the figure is not limited to a field effect transistor but is another active element such as a bipolar transistor.

FIG. 2 is a circuit diagram showing a second embodiment of the mixer circuit according to the present invention, wherein 201 is an image signal suppressing inductor, 202 and 203 are current source transistors, and 204 is a variation absorption resistor. 1 and FIG.
The same reference numerals are given to the portions corresponding to and the duplicate description will be omitted.

The mixer circuit shown in the figure is different from the circuit diagram showing the first embodiment shown in FIG.
The sources of the distortion improving resistors 11 and 16 are
8, 119, the drains of the current source transistors 202 and 203 whose gates are grounded are connected,
The sources of the current source transistors 202 and 203 are commonly connected.
The image signal suppression inductor 201 is inserted between the respective drains.

In the above-described second embodiment, the same effects as those of the first embodiment can be obtained. In addition, by inserting an inductor between the sources of the RF buffer transistors 116 and 117, an RF signal can be obtained. For an image signal in a higher frequency band, the feedback amount becomes large and the conversion gain in the image band becomes small, so that a mixer circuit having excellent image suppression characteristics can be obtained.

FIG. 5 shows an example of a CATV frequency band in which the conventional mixer is used. For an RF signal band of 55 to 860 MHz, the intermediate frequency signal frequency is set to one.
When the frequency is 100 MHz, the image signal frequency band is 22
Since the value of the inductor is 55 to 3060 MHz, and the value of the inductor required to suppress the image frequency band is about several nH, which can be easily integrated, it is possible to integrate a mixer circuit having an image signal suppressing means.

FIG. 3 is a circuit diagram showing a third embodiment of a mixer circuit according to the present invention, wherein 301 is a chip capacitor, 302 is an equivalent inductor of the chip capacitor 301, 303 is an equivalent capacitance of the chip capacitor 301, and 30
Reference numeral 4 denotes a feedback resistor, and portions corresponding to FIGS. 1 and 5 are denoted by the same reference numerals, and redundant description will be omitted.

Compared to the circuit diagram of the first embodiment shown in FIG. 1, the mixer circuit shown in FIG. 1 has an RF signal input terminal 102 grounded at a high frequency by a chip capacitor 301 comprising an equivalent inductor 302 and an equivalent capacitor 303. ,further,
The RF signal input terminal 102 is connected via a feedback resistor 304 to a connection point between the NF inserted between the drains of the RF buffer transistors 116 and 117 and the distortion improvement capacitors 114 and 115. Further, the RF signal is supplied to the RF signal input terminal 1
01 is input as an unbalanced signal.

In the third embodiment, since the connection point of the NF and the distortion improvement capacitors 114 and 115 is grounded via the feedback resistor 304 and the chip capacitor 301, the local oscillation signal goes to the drain side of the RF buffer transistor. Can be suppressed even if they are in phase or out of phase with each other, so that deterioration of NF characteristics and secondary distortion characteristics can be suppressed, and output to both drains of the RF buffer transistor. By applying a feedback to the unbalanced component of the RF signal by using the small inductor component of the high-frequency ground capacitance of the RF input terminal, the balance of the RF signal is improved.
At 0, 111, 112, and 113, it is possible to improve the second-order distortion characteristics generated by imbalance of the RF signal input at the time of frequency conversion.

FIG. 4 is a circuit diagram showing a fourth embodiment of a mixer circuit according to the present invention, wherein 401 is an image signal suppressing inductor, 402 and 403 are current source transistors, and 404 is a variation absorption resistor. 3, parts corresponding to those in FIG. 5 are denoted by the same reference numerals, and redundant description is omitted.

The mixer circuit shown in the figure is different from the circuit diagram showing the third embodiment shown in FIG.
The sources of the distortion improving resistors 11 and 16 are respectively
8 and 119, the drains of the current source transistors 402 and 403 whose gates are grounded are connected,
The sources of the current source transistors 402 and 403 are commonly connected. The common connection point is grounded by a variation absorption resistor 404, and an image signal suppressing inductor 401 is inserted between the respective drains.

In the above-described fourth embodiment, the same effect as that of the third embodiment can be obtained. In addition, by inserting an inductor between the sources of the RF buffer transistors 116 and 117, an RF signal can be obtained. For an image signal in a higher frequency band, the feedback amount becomes large and the conversion gain in the image band becomes small, so that a mixer circuit having excellent image suppression characteristics can be obtained.

Next, the effect of each embodiment of the present invention will be described with reference to FIGS. FIG. 6 shows the NF characteristics of the mixer circuits shown in FIGS. 1, 3 and 5, and FIG. 7 shows the NF characteristics of the mixer circuits shown in FIGS. 1, 3 and 5.
The experimental results of the secondary distortion characteristics are shown.

In FIG. 6 and FIG.
For the F signal frequency of 55 to 860 MHz, the power supply voltage is 5
V, the input signal level is -15 dBm, the local oscillation signal frequency is 1155 to 1960 MHz, and the output intermediate frequency signal frequency is 1100 MHz.

In FIG. 6, the horizontal axis indicates the RF signal frequency, and the vertical axis indicates the noise figure. As shown in FIG.
By adopting the configuration of the mixer circuit shown in FIG. 3, the NF characteristic deterioration can be suppressed as compared with the mixer circuit shown in the related art.

In FIG. 7, the horizontal axis indicates the RF signal frequency, and the vertical axis indicates the secondary distortion characteristics. As shown in FIG. 7, by employing the configuration of the mixer circuit shown in FIGS. 1 and 3, deterioration of the secondary distortion characteristic can be suppressed as compared with the mixer circuit shown in the related art.

Next, a receiving circuit using the mixer circuit according to the above embodiment will be described with reference to FIG. FIG.
FIG. 1 shows a block diagram of a receiving circuit of a cable television (CATV). The receiving circuit shown in FIG.
01, bandpass filters 802, 808 and 81
4. Gain control amplifier circuit 803, up-converter mixer 804, up-converter local oscillator circuit 807, intermediate frequency signal amplifier circuits 809 and 815, down-converter mixer 810, down-converter local oscillator circuit 81
3, low-pass filter 816, intermediate frequency signal output terminal 8
17 are provided.

An up-converter mixer 80 shown in FIG.
4 has an RF buffer 805 and a mixer 806, and the down-converting mixer 810 has an RF buffer 811 and a mixer 812. The up-converter mixer 804 uses the mixer circuit shown in FIG. 1, FIG. 2, FIG. 3, or FIG.

In the receiving circuit shown, the RF signal input terminal 80
The unnecessary RF band other than the RF signal band is attenuated by the band-pass filter 802 and then amplified by the gain control amplifier circuit 803, and input to the up-converter mixer 804. . After being amplified by the RF buffer 805, the RF signal is up-converted in the mixer 806 by the local oscillation signal from the up-conversion local oscillation circuit 807 to a first intermediate frequency signal in the 1 GHz band higher than the RF signal band. You.

The band of the up-converted first intermediate frequency signal is selected by the band-pass filter 808 for the selected receiving channel, and then amplified by the intermediate frequency signal amplifying circuit 809. The down-converting mixer 81
Input to 0. The first intermediate frequency signal input to the down-converting mixer 810 is amplified by the RF buffer 811 and then, in the mixer 812, output by the local oscillation signal from the down-converting local oscillation circuit 813.
The signal is down-converted to a second intermediate frequency signal in the 0 to 50 MHz band.

The second intermediate frequency signal is supplied to the band-pass filter 8.
After the unnecessary band is attenuated by 14, the signal is amplified by the intermediate frequency signal amplifying circuit 815, and after the low-pass filter 816 attenuates a frequency higher than the second intermediate frequency signal,
It is output from the second intermediate frequency signal output terminal 817. In the receiving circuit shown in the figure, the second intermediate frequency signal output terminal 8 is connected to the RF signal level input to the RF signal input terminal 801.
Gain control is performed by the gain control amplification circuit 803 so that the level output from 17 is constant.

In the CATV receiving circuit shown in FIG.
Since a multi-channel RF signal of several tens of channels or more is input to a wide band of 860 MHz, an up-converter mixer having a wide band and low distortion characteristics is required. For this reason, when the conventional mixer circuit is applied to the up-converter mixer 804, the distortion characteristic is degraded by the reception frequency. Therefore, two or more systems of the band-pass filter 802 inserted in the RF signal input unit are provided. The up-converter mixer 8
It is necessary to limit the number of channels input to 04. If the mixer circuit according to the present embodiment is used, the distortion characteristics do not deteriorate and there is no need to provide a plurality of band-pass filters 802, so that a CATV receiving circuit that does not require reception band switching can be obtained.

[0047]

According to the present invention, by suppressing the leakage of the local oscillation signal input to the mixer to the RF signal input side (RF buffer transistor side), the deterioration of the NF characteristic and the deterioration of the secondary distortion characteristic are suppressed. A small number of mixer circuits can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a mixer circuit according to the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of a mixer circuit according to the present invention.

FIG. 3 is a circuit diagram showing a third embodiment of a mixer circuit according to the present invention.

FIG. 4 is a circuit diagram showing a third embodiment of a mixer circuit according to the present invention.

FIG. 5 is a circuit diagram showing an example of a conventional mixer circuit.

FIG. 6 is a characteristic diagram showing a difference in noise figure characteristics between a conventional mixer circuit and a mixer circuit according to the present invention.

FIG. 7 is a characteristic diagram showing a difference in a secondary distortion characteristic between a conventional mixer circuit and a mixer circuit according to the present invention.

FIG. 8 is a block diagram illustrating an example of a receiving circuit using an embodiment of the present invention.

[Explanation of symbols]

101, 102: RF signal input terminal, 103: Power supply terminal, 108: Intermediate frequency output terminal, 110, 111, 11
2,113 ... frequency conversion transistors, 114, 11
5,501 ... NF, distortion improvement capacity, 116,117 ... RF
Buffer transistor, 118, 119 ... distortion improvement resistance,
Reference numerals 120, 202, 203, 402, 403: current source transistors, 122: power supply ground capacitance, 127, 128: local oscillation signal input terminals, 201, 401: image signal suppressing inductors, 301: chip capacitors, 304: feedback resistors.

 ──────────────────────────────────────────────────続 き The continuation of the front page F term (reference) 5K020 AA02 AA03 AA05 BB06 DD09 FF13

Claims (5)

[Claims] A first transistor in which a drain of a third transistor is commonly connected to sources of the first and second transistors.
, A second differential circuit in which the drain of a sixth transistor is commonly connected to the sources of the fourth and fifth transistors, and a first current source. The source of the transistor and the source of the sixth transistor are connected to a first current source, and the gates of the first and fifth transistors are connected to a first input terminal.
Connected to the second input terminal of the transistor
A local oscillation signal is input from between the first and second input terminals, and the gates of the third and sixth transistors are connected to third and fourth input terminals, respectively. A radio frequency signal is input from between input terminals, and the radio frequency signal is converted from the connection point between the drains of the first and fourth transistors and the connection point between the drains of the second and fifth transistors by the local oscillation signal. In a double-balanced mixer circuit that outputs an intermediate frequency signal obtained by frequency conversion, a series-connected body including first and second capacitors is provided between a drain of the third transistor and a drain of the sixth transistor. A mixer circuit, wherein the connection is made and the connection point between the first and second capacitors is grounded. 2. A first transistor in which a drain of a third transistor is commonly connected to sources of the first and second transistors.
A second differential circuit in which a drain of a sixth transistor is connected to a source of the fourth and fifth transistors in common, and a second and a third current source. Third
And the source of the sixth transistor is connected to the second and third current sources, respectively.
The gates of the first and fifth transistors are connected to a first input terminal, and the gates of the second and fourth transistors are connected to a second input terminal. A local oscillation signal is input, and the gates of the third and sixth transistors are connected to third and fourth input terminals, respectively.
A radio frequency signal is input between the third and fourth input terminals, and the radio frequency signal is input between a connection point between the drains of the first and fourth transistors and a connection point between the drains of the second and fifth transistors. In a double-balanced mixer circuit that outputs an intermediate frequency signal obtained by frequency-converting a signal using the local oscillation signal, a first and a second transistor are disposed between the drain of the third transistor and the drain of the sixth transistor. A series connection body including a capacitor is connected, a connection point between the first and second capacitors is grounded, and a source of the third transistor and a source of the sixth transistor are connected by an inductor. Mixer circuit. 3. A first transistor in which the drain of a third transistor is commonly connected to the sources of the first and second transistors.
, A second differential circuit in which the drain of a sixth transistor is commonly connected to the sources of the fourth and fifth transistors, and a first current source. The source of the transistor and the source of the sixth transistor are connected to a first current source, and the gates of the first and fifth transistors are connected to a first input terminal.
Connected to the second input terminal of the transistor
A local oscillation signal is input from between the first and second input terminals, and the gates of the third and sixth transistors are connected to third and fourth input terminals, respectively. A radio frequency signal is input from between input terminals, and the radio frequency signal is converted from the connection point between the drains of the first and fourth transistors and the connection point between the drains of the second and fifth transistors by the local oscillation signal. In a double-balanced mixer circuit that outputs an intermediate frequency signal obtained by frequency conversion, a series-connected body including first and second capacitors is provided between a drain of the third transistor and a drain of the sixth transistor. And a connection point between the first and second capacitors and a gate of a third transistor connected by a resistor, and a third input terminal connected to the radio frequency signal by a circuit including at least a capacitor. Mixer circuit, characterized in that the high-frequency ground have. 4. A first transistor in which the drain of a third transistor is commonly connected to the sources of the first and second transistors.
A second differential circuit in which a drain of a sixth transistor is connected to a source of the fourth and fifth transistors in common, and a second and a third current source. Third
And the source of the sixth transistor are connected to the second and third current sources, respectively, and the gates of the first and fifth transistors are connected to a first input terminal, and the second and second transistors are connected to the first input terminal. 4 is connected to the second input terminal, a local oscillation signal is input between the first and second input terminals, and the gates of the third and sixth transistors are connected to the third and third transistors, respectively. 4 and a radio frequency signal is input between the third and fourth input terminals, and a connection point between the drains of the first and fourth transistors and the second and fifth transistors are connected. In a double-balanced mixer circuit that outputs an intermediate frequency signal obtained by converting the frequency of the radio frequency signal by the local oscillation signal from between the connection points of the drains, the drain of the third transistor and the sixth The first between the drain of the transistor 1
And a series connection body composed of a second capacitor, a connection point between the first and second capacitors and a gate of a third transistor connected by a resistor, and a third input terminal connected to the radio frequency signal. A high frequency grounding circuit including at least a capacitor, and a source of the third transistor and a source of the sixth transistor are connected by an inductor. 5. A receiving circuit having a mixer circuit for outputting an intermediate frequency signal obtained by frequency-converting a received signal by a local oscillation signal, wherein at least the mixer circuit according to any one of claims 1 to 4 is used. A receiving circuit, characterized in that: