JP3343223B2 - Image suppression mixer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving mixer for generating an intermediate frequency signal by mixing a radio frequency signal and a local oscillation signal, and more particularly to an image signal suppressing image signal for obtaining an intermediate frequency signal without spurious signals. It relates to a possible image suppression mixer.

[0002]

2. Description of the Related Art In communication equipment and broadcasting equipment, a reception mixer for converting an RF signal received by an antenna into an intermediate frequency signal in order to amplify or demodulate the signal stably is widely used. The mixer multiplies the radio frequency signal RF and the local oscillation signal LO, and converts the frequency component of the difference between the radio frequency signal RF and the local oscillation signal LO into the intermediate frequency signal IF.
Is generated as In the frequency conversion by the mixer, harmonics of the radio frequency signal RF and the local oscillation signal LO are internally generated due to the non-linearity and the wide band characteristics, and the frequency of the difference is also output as the intermediate frequency signal IF.
Therefore, the radio frequency signal RF radio frequency f _RF, the local oscillation signal LO of the local oscillation frequency f _LO, and the intermediate frequency signals I
The relation of the intermediate frequency f _IF of F is as shown in the following equation (1). f _IF = mf _RF + nf _LO (1) where m, n = 0, ± 1, ± 2, ...

For example, in a mixer used for a receiver of a lower heterodyne system in which a local oscillation frequency f _LO is set lower than a desired radio frequency f _RF , m = 1, n = −1
In this case, the intermediate frequency f _IF (= f _RF −f _LO ) is selected. At this time, the radio frequency f _RF (= f _LO −f _IF ) represented by m = −1, n = 1 is called an image frequency, and an unnecessary wave of this image frequency (that is, an image signal) is a radio frequency signal. It is input as RF, to be converted to the same intermediate frequency f _IF and the desired wave by mixer. Harmonic components include the original radio frequency f _RF and local oscillation frequency f _LO
, It can be relatively easily removed by a filter or the like. However, the intermediate frequency f
_{Since the IF} is usually set to a frequency that is at least one digit lower than the radio frequency f _RF , the image frequency is close to the desired radio frequency f _RF , and it is difficult to remove this image frequency with a high frequency circuit. is there. For this reason, suppressing the conversion of the image signal input as the image frequency into the intermediate frequency signal IF is an important issue in improving the characteristics of the mixer.

FIG. 2 is a configuration diagram of a conventional image suppression mixer. This image suppression mixer is used for a lower heterodyne type receiver or the like, and outputs a terminal 1 to which a radio frequency signal RF is input, a terminal 2 to which a local oscillation signal LO is input, and an intermediate frequency signal IF. Terminal 3
have. In-phase distributor 10 is connected to terminal 1. The in-phase distributor 10 is called a Wilkinson-type in-phase distributor, and converts an input radio frequency signal RF into inductors 12 and 13, a resistor 14, and capacitors 15 and 1.
6 and is divided into two systems of signals having the same level and phase. Nodes N11 and N12 on the two output sides of the in-phase distributor 10 are unit mixers 30 ₁ and 3 respectively.
0 ₂ is connected to the first input side.

[0005] The terminal 2 is connected to a phase shift distributor 70. The phase shifter 70 is a combination of a Wilkinson-type in-phase splitter and a phase shifter using an LC filter. The phase shifter 70 divides the local oscillation signal LO and outputs two signals having the same level and different phases by 90 °. It is. Node of the output side of the phase splitter 70 N71, N72 are connected to the second input of unit mixers ₃₀ 1, 30 _2, respectively. The unit mixers 30 ₁ and 30 ₂ multiply a signal supplied to a first input side and a signal supplied to a second input side, and output a signal of a result of the multiplication. By these unit mixers 30 ₁ and 30 ₂ , two sine waves having different frequencies are multiplied, and a combined signal of a sum frequency component and a difference frequency component is output. The output sides of the unit mixers 30 ₁ and 30 ₂ are connected to the input side of the hybrid circuit 90.

The hybrid circuit 90 is a four-terminal circuit composed of capacitors 91 to 93 on the input side, capacitors 96 to 98 on the output side, and inductors 94 and 95 connecting them. It outputs a signal whose phase is shifted by 90 ° and added to the other input signal. A load resistor 99 is connected to a first output side of the hybrid circuit 90, and a second output side is connected to the terminal 3. The terminal 1 of this image suppression mixer has an angular frequency ω
When one of the radio frequency signal RF is input, the radio frequency signal RF is divided by the phase distributor 10 are inputted in a unit mixer 30 _1, 30 ₂ in the same phase. On the other hand, terminal 2
When the local oscillation signal LO of angular frequency ω2 is input, this local oscillation signal LO is divided by the phase splitter 70, the unit mixers 30 _1, 30 _2, is input with a phase difference of [pi / 2 . As a result, the phase angles of the signals output from the unit mixers 30 ₁ and 30 ₂ are (mω1 + nω
2) t and (mω1 + nω2) t + nπ / 2,
It has a phase difference of nπ / 2. These signals are further given a phase difference of π / 2 by the hybrid circuit 90,
The signals are added at a phase difference of (n + 1) π / 2, and become an intermediate frequency signal IF. Here, the image signals are m = -1, n =
Since it is represented by 1, the phase difference of the intermediate frequency signal IF is π, that is, the phase difference is opposite. Therefore, the intermediate frequency signals IF generated by the image signal cancel each other out, and are not output from the terminal 3. On the other hand, the desired radio frequency signal R
The phase difference of the intermediate frequency signal IF generated from F becomes zero, is synthesized, and is output from the terminal 3.

[0007]

In an image suppression mixer, it is necessary to minimize the conversion of an image signal into an intermediate frequency signal IF and output. In the image suppression mixer, an image suppression ratio (IR) which is a ratio of an image signal to a radio frequency signal RF is represented by a phase deviation (θ).
And the gain deviation (G), it can be expressed as the following equation (2).

(Equation 1) That is, in order to increase the image suppression ratio, it is necessary to minimize the phase deviation and the gain deviation.

However, in the conventional image suppression mixer, it is difficult to reduce the phase deviation and the gain deviation due to variations in the values of circuit elements such as capacitors and inductors that constitute the phase shift distributor 70 and the hybrid circuit 90. there were. SUMMARY OF THE INVENTION The present invention solves the problems of the prior art and provides an image suppression mixer having a high image suppression ratio.

[0009]

In order to solve the above-mentioned problems, a first aspect of the present invention is to provide an image suppression mixer in which a first high-frequency input signal is distributed to two systems so that a level and a phase are adjusted. An in-phase distributor that outputs the same first and second in-phase signals; and a second high-frequency input signal that is divided into two systems to be equal in level to the first phase-shifted signal and the second phase-shifted signal. A phase-shift distributor that outputs a second phase-shifted signal whose phase is delayed by 90 °, and a first phase-shifter that mixes the first in-phase signal and the first phase-shifted signal to generate a first mixed signal. , A second unit mixer that mixes the second in-phase signal and the second phase- shifted signal to generate a second mixed signal, and a phase of 45 ° from the first mixed signal . A first intermediate signal that is delayed is generated, and a phase of 4
5 ° proceeds and phase shifters first intermediate signal and level to produce a second intermediate signal that is equal, the first and second intermediate signals
Cancels out the components that are 180 ° out of phase,
A source that synthesizes and amplifies in-phase components and outputs an intermediate frequency signal
And a follower-type amplifier.

According to a second aspect of the present invention, the phase shift distributor according to the first aspect of the present invention is a first phase shifter comprising a first resistor and a first capacitor.
And a first differential circuit comprising a second resistor having a resistance equal to the first resistor and a second capacitor having a capacitance equal to the first capacitor. In addition, the phase shifter includes a second integrating circuit including a third resistor and a third capacitor, a fourth resistor having a resistance equal to the third resistor, and a capacitance equal to the third capacitor. The fourth with
And a second differentiating circuit composed of the above-mentioned capacitors. In a third aspect , the in-phase distributor, the phase shift distributor, the first and second unit mixers, the phase shifter, and the amplifier according to the first or second aspect are formed on the same semiconductor substrate. are doing.

According to the present invention, since the image suppressing mixer is configured as described above, the following operation is performed.
The first high-frequency input signal input to the in-phase distributor is divided into two systems, and first and second in-phase signals having the same level and phase are output. On the other hand, the second high-frequency input signal input to the phase shift distributor is, for example, a first integrating circuit and a first high-frequency signal.
And the first and second phase-shifted signals having a phase difference of 90 ° are output. The first in-phase signal and the first phase-shifted signal are mixed by a first unit mixer to generate a first mixed signal. The second in-phase signal and the second phase-shifted signal are mixed by the second unit mixer to generate a second mixed signal. The first and second mixed signals are input to, for example, a phase shifter including a second integrating circuit and a second differentiating circuit, and the first and second mixed signals have a phase difference of 90 °.
Is generated. The first and second intermediate signals are combined by an amplifier, and an intermediate frequency signal is output.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment FIG. 1 is a block diagram of an image suppression mixer according to a first embodiment of the present invention. This image suppression mixer is formed on a one-chip semiconductor substrate and is used for a lower heterodyne type receiver or the like.
A terminal 1 to which an 84 GHz radio frequency signal RF is input;
5. Terminal 2 to which local oscillation signal LO of 80 GHz is input
And outputs an intermediate frequency signal IF of 40 MHz to the terminal 3 on the output side. The terminal 1 is connected to a Wilkinson-type in-phase distributor 10. In-phase distributor 1
0 is a capacitor 11 between the input side and the ground potential GND.
Are connected, and the input side and output side nodes N1
1 and N12 are connected by inductors 12 and 13, respectively. A resistor 14 is connected between the nodes N11 and N12, and capacitors 15 and 16 are connected between the nodes N11 and N12 and the ground potential GND, respectively. The inductors 12 and 13 have the same inductance LW, and the capacitors 15 and 16 are set to have the same capacitance CW2.
The first and second in-phase signals RF1 and RF2 having the same level and phase are output to the two nodes N11 and N12, respectively.

The in-phase distributor 10 has a capacitance CW2, an inductance LW, and a capacitor 11
And the resistance value RW of the resistor 14
And the angular frequency ω1 of the radio frequency signal RF are set so as to satisfy the following equations (3) to (5). LW = Z0 / ω1 (3) CW1 = 2 · CW2 = 2 // (Z0 · ω1) (4) RW = 2 · Z0 (5) where Z0 is the reference impedance terminal 2. Is connected to the phase shift distributor 20. The phase shift distributor 20 includes an integrating circuit including a resistor 21 and a capacitor 22 provided between an input side and an output side node N21, and a capacitor 23 provided between an input side and an output side node N22. It is composed of a differentiating circuit using a resistor 24. The resistance values R1 and R2 of the resistors 21 and 24 are set to 100Ω, respectively, and the capacitances C1 and C2 of the capacitors 22 and 23 are set to 0.275 pF, respectively. As a result, the local oscillation signal LO of 5.80 GHz is output to the node N21 as a phase shift signal LO1 with a phase delayed by π / 4, and is output to the node N22 as a phase shifted signal LO2 with a phase advanced by π / 4. You. That is,
Signals having a phase difference of π / 2 are output to the nodes N21 and N22. Note that the resistance values R1, R2 and the capacitance C of the phase shift distributor 20
1, C2, and the angular frequency ω2 of the local oscillation signal LO are set so as to satisfy the following equations (6) and (7). R1 · C1 = R2 · C2 = 1 / ω2 (6) R1 = R2, C1 = C2 (7) The node N11 of the in-phase distributor 10 and the node N21 of the phase-shift distributor 20 are units. It is connected to the input side of the mixer 30 _1. Further, the node N12 of the in-phase distributor 10, the node N22 of the phase distributor 20 is connected to the input side of the unit mixer 30 _2.

[0014] In the unit mixer 30 _1, node N11, N
21 are coupled to coupling capacitors 31,
The signal is supplied to first and second gates of a dual-gate type field-effect transistor (hereinafter, referred to as “FET”) 33 through the line 32. An inductor 34 and a resistor 35 are connected between the first and second gates of the FET 33 and the ground potential GND, respectively, and a resistor 36 and a capacitor 37 are connected in parallel between the source and the ground potential GND. I have. The drain of the FET 33 is
The power supply potential VDD is connected via a load inductor 38. In the unit mixer 30 _1, signals corresponding to the product of the first and second voltage applied to the gate of FET33 is, mixed signals MX1 from the drain of the FET33
Is output. Unit mixer 30 ₂
Also it has a unit mixer 30 ₁ of the same configuration, from this unit mixer 30 _2, mixed signal MX2 corresponding to the product of the signal provided from the node N12, N22 are to be outputted. The output sides of the unit mixers 30 ₁ and 30 ₂ are connected to the first and second input sides of the phase shifter 40, respectively.

The phase shifter 40 includes a differentiating circuit including a capacitor 41 and a resistor 42 provided between a first input side and a first output side node N41, and a second input side and a second output side. And an integrating circuit including a resistor 43 and a capacitor 44 provided between the node N42. Resistance 4
2 and 43 are set to 1000Ω, respectively, and the capacitances C and
3 and C4 are each set to 3.98 pF.
As a result, the 40 MHz intermediate frequency signal IF is output to the node N41 as the intermediate signal IF1 with the phase advanced by π / 4, and is output to the node N42 as the intermediate signal IF2 with the phase delayed by π / 4. That is, nodes N41 and N41
At 42, a signal having a phase difference of -π / 2 is output.

The resistance value R of the phase shifter 40 is
3, R4, capacitor C3, C4, and the relationship of the intermediate frequency signal IF of angular frequency omega _IF is the following (8), are set so as to satisfy the expression (9). R3 · C3 = R4 · C4 = 1 / ω _IF (8) R3 = R4, C3 = C4 (9) The differential amplifier 50 is connected to the nodes N41 and N42 on the output side of the phase shifter 40. Is connected. The differential amplifier 50 is
T51, 52, and these FETs 51, 52
Are connected to nodes N41 and N42, respectively. Bias voltage supply resistors 53 and 54 are connected between the gate of the FET 51 and the power supply potential VDD and the ground potential GND, respectively. A resistor is connected between the gate of the FET 52 and the power supply potential VDD and the ground potential GND, respectively. 55 and 56 are connected. An inductor 5 is connected between the drains of the FETs 51 and 52 and the power supply potential VDD.
7, 58 are connected. The sources of the FETs 51 and 52 are connected to the ground potential GND via the FET 59 forming a constant current circuit, and the drains are connected to the terminal 3.

Next, the operation will be described. When a radio frequency signal RF having an angular frequency ω1 is input to the terminal 1 of the image suppression mixer, the radio frequency signal RF is supplied to the in-phase distributor 10.
, The in-phase signals RF1, R having the same phase and level
F2, which is provided to the unit mixers 30 ₁ and 30 ₂ . On the other hand, when the local oscillation signal LO having the angular frequency ω2 is input to the terminal 2, the local oscillation signal LO is
Is divided into phase shift signals LO1 and LO2 having the same level and a phase difference of π / 2,
0 _1, applied to 30 _2. In the unit mixer 30 _1, mixed signal MX1 is generated is multiplied in-phase signal RF1 and phase shift signal LO1. Also, the unit mixer 30 ₂
Then, the in-phase signal RF2 and the phase shift signal LO2 are multiplied to generate a mixed signal MX2. These mixed signals M
X1 and MX2 have the same level, and (mω1 + n
ω2) t and (mω1 + nω2) t + nπ / 2. Here, m and n represent the harmonic order of the radio frequency signal RF and the local oscillation signal LO, respectively.

The mixed signals MX1 and MX2 are input to a phase shifter 40 that gives a phase difference of -π / 2, and the phase angles of the intermediate signals IF1 and IF2 output from the phase shifter 40 are (mω1 + nω2), respectively. t and (mω1 + nω2) t
+ Nπ / 2−π / 2. Accordingly, the intermediate signals IF1 and IF2 having the same level and having a phase difference of (n-1) π / 2 are input to the differential amplifier 50. Here, the intermediate signal converted from the desired radio frequency signal RF is m = 1, n
= -1, and the intermediate signal converted from the image signal is represented by m = -1, n = 1. Thereby, the phase difference between the intermediate signals IF1 and IF2 generated from the radio frequency signal RF becomes π, and the phase difference between the intermediate signals generated from the image signal becomes 0. In the differential amplifier 50, two signals with a phase difference of π are combined and output, and two signals with a phase difference of 0 cancel each other and are not output. Therefore, the intermediate signal converted from the image signal is canceled by the differential amplifier 50. Then, only the intermediate signals IF1 and IF2 converted from the desired radio frequency signal RF are combined by the differential amplifier 50 and output from the terminal 3 as the intermediate frequency signal IF.

FIG. 3 is a characteristic diagram showing the relationship between the variation of the constant and the gain error and the phase error in the phase shift distributor 20 in FIG. On the horizontal axis of FIG. 3, the fluctuations (unit: from the design values) of the resistance values R1, R2 and the capacitances C1, C2 are shown.
%), And the vertical axis indicates a gain error (unit: dB) and a phase error (unit: °). The broken line in the figure indicates the characteristic of the gain error, and the thick line indicates the characteristic of the phase error. Since the resistors 21 and 24 and the capacitors 22 and 23 are formed on the same semiconductor substrate, the resistance values R1 and R
2, and the capacitances C1 and C2 are assumed to be equal.

FIG. 4 is a diagram showing the relationship between the variation of the constant and the gain error and the phase error in the phase shifter 40 in FIG.
The horizontal axis of FIG. 4 shows the variation of the resistance values R3, R4 and the capacitances C3, C4 from the design values, and the vertical axis shows the gain error and the phase error. The broken line in the figure indicates the characteristic of the gain error, and the thick line indicates the characteristic of the phase error.
It is assumed that the resistances R3 and R4 of the resistors 42 and 43 and the capacitances C3 and C4 of the capacitors 41 and 44 are equal.

As is apparent from FIGS. 3 and 4, even if the resistance value and the capacitance change, no phase error occurs. On the other hand, due to fluctuations in resistance and capacitance,
A gain error occurs. This gain error has opposite characteristics between the phase shift distributor 20 and the phase shifter 40. In this image suppression mixer, the phase shift distributor 20 and the phase shifter 40 are formed on the same semiconductor substrate. Therefore, when the resistance value and the capacitance fluctuate due to the variation in the manufacturing process, the fluctuation is caused by the phase shift distribution. The same occurs in the shifter 20 and the phase shifter 40. Therefore, the gain error caused by the phase shift distributor 20 and the gain error caused by the phase shifter 40 cancel each other, and almost no gain error occurs as a whole.

As described above, the lower heterodyne type image suppressing mixer according to the first embodiment has a phase shifter 20 for providing a phase difference to the local oscillation signal LO and a frequency-converted mixed signal MX. A phase shifter 40 for giving a phase difference
Each is composed of an integrating circuit and a differentiating circuit for giving a phase shift of ± π / 4 by means of a resistor and a capacitor. Further, the phase shift distributor 20 and the phase shifter 40 are configured to give opposite phase shift amounts. Therefore, even if the value of the resistor or the capacitor fluctuates, the gain error of the two signal paths caused by the fluctuation is canceled out, and the level of the two intermediate signals IF1 and IF2 input to the differential amplifier 50 can be kept equal. it can. Further, a phase error hardly occurs due to a change in the value of the resistor or the capacitor. Therefore, there is an advantage that frequency conversion with a high image suppression ratio can be performed without being affected by variations in the values of the resistance and the capacitor. Further, since the intermediate signals IF1 and IF2 are synthesized and amplified by the differential amplifier 50, there is an advantage that a high-level intermediate frequency signal IF can be obtained.

Second Embodiment FIG. 5 is a block diagram of an image suppressing mixer according to a second embodiment of the present invention. Elements common to those in FIG. 1 are denoted by the same reference numerals. . This image suppression mixer
It is formed on a one-chip semiconductor substrate and is used for an upper heterodyne type receiver or the like. For example, a radio frequency signal RF of 5.76 GHz and a radio frequency signal of 5.80 GHz
It generates and outputs a 40 MHz intermediate frequency signal IF from the z local oscillation signal LO. The difference between the image suppression mixer of this embodiment and the image suppression mixer of FIG. 1 is that a source follower type amplifier 60 is provided instead of the differential amplifier 50 in FIG. Same as 1.

The amplifier 60 has FETs 61 and 62, and the gates of the FETs 61 and 62 are connected to nodes N41 and N42 of the phase shifter 40, respectively.
The gate of the FET 61 and the power supply potential VDD and the ground potential GN
D, a resistor 6 for supplying a bias voltage.
3, 64 are connected, and the gate of the FET 62 and the power supply potential V
DD and the ground potential GND, respectively.
5, 66 are connected. The drains of the FETs 61 and 62 are connected to the power supply potential VDD.
The sources of 62 are commonly connected and connected to the ground potential GND via the FET 67 forming a constant current circuit.
The sources of the FETs 61 and 62 are connected to the terminal 3. In such a source-follower type amplifier 60, two signals having the same phase are synthesized and output, and two signals having a phase difference of π cancel each other and are not output.

Next, the operation will be described. The radio frequency signal RF having the angular frequency ω1 input to the terminal 1 of the image suppression mixer is divided into in-phase signals RF1 and RF2 having the same phase and level by the in-phase distributor 10, and the unit mixer 3
0 _1, applied to 30 _2. On the other hand, the local oscillation signal LO having the angular frequency ω2 input to the terminal 2 is divided by the phase shift distributor 20 into phase shift signals LO1 and LO2 having the same level and a phase difference of π / 2, and the unit mixer 30 ₁ , 3
0 ₂ In the unit mixer 30 _1, the in-phase signal RF1 and the phase shift signal LO1 is mixed, mixed signal MX1
Is generated. Further, a unit mixer 30 _2, phase signals R
F2 and the phase shift signal LO2 are mixed to generate a mixed signal MX2. The levels of the mixed signals MX1 and MX2 are equal, and (mω1 + nω2) t and (mω1 + n
ω2) A signal having a phase angle of t + nπ / 2.

The mixed signals MX1 and MX2 are further supplied to the phase shifter 4
0, and the phase angles of the intermediate signals IF1 and IF2 output from the phase shifter 40 are (mω1 + nω
2) t and (mω1 + nω2) t + nπ / 2−π / 2
Becomes Therefore, the amplifier 60 has a phase difference of (n-1) π / 2 and the intermediate signals IF1 and IF2 having the same level.
Is entered. In the upper heterodyne, an intermediate signal IF1, which is converted from a desired radio frequency signal RF,
IF2 is represented by m = -1, n = 1, and the intermediate signal converted from the image signal is represented by m = 1, n = -1. Thereby, the intermediate signal I generated from the radio frequency signal RF
The phase difference between F1 and IF2 is 0, and the phase difference of the intermediate signal generated from the image signal is π. In the amplifier 60, two signals having a phase difference of 0 are synthesized and output, and two signals having a phase difference of π are canceled and output. Therefore, the intermediate signal converted from the image signal is canceled, and the intermediate signal I converted from the desired radio frequency signal RF is canceled.
Only F1 and IF2 are synthesized by the amplifier 60 and output from the terminal 3 as the intermediate frequency signal IF.

As described above, the upper heterodyne type image suppressing mixer of the second embodiment has the same phase shift distributor 20 and phase shifter 40 as in the first embodiment. Therefore, even if the values of the resistors and capacitors constituting these components fluctuate, the gain errors of the two signal paths caused by the variations are canceled out, and the levels of the two intermediate signals IF1 and IF2 input to the amplifier 60 are kept equal. Can be. Further, a phase error hardly occurs due to a change in the value of the resistor or the capacitor. Therefore, there is an advantage similar to that of the first embodiment.

Note that the present invention is not limited to the above embodiment, and various modifications are possible. For example, there are the following modifications (a) to (f). (A) In the image suppression mixers shown in FIGS. 1 and 5, the radio frequency signal RF is input to the terminal 1 and the local oscillation signal LO is input to the terminal 2. The same operation and effect can be obtained by inputting the local oscillation signal LO and inputting the radio frequency signal RF to the terminal 2. (B) The in-phase distributor 10 is not limited to the Wilkinson type. Any configuration can be applied as long as the input signal can be distributed to two signals having the same level and phase. (C) The unit mixers 30 ₁ and 30 ₂ are not limited to those using the dual-gate type FET 33 as shown. Any configuration can be applied as long as it multiplies two input signals and outputs a signal resulting from the multiplication. (D) The differential amplifier 50 is not limited to the configuration shown in FIG. Any configuration may be applied as long as it removes the in-phase component and outputs the opposite-phase component. (E) The amplifier 60 is not limited to the configuration shown in FIG. Any configuration can be applied as long as it outputs an in-phase component after removing the anti-phase component. (F) For example, the unit mixers 30 ₁ and 30 ₂ and the phase shifter 4
Between 0 and 0, a filter for removing unnecessary harmonic components may be inserted.

[0029]

As described above in detail, according to the first aspect, the phase shift distributor for distributing the second high-frequency input signal into two systems of signals having phases different from each other by 90 ° is provided. A phase shifter that shifts the phase of a synthesized signal output from the unit mixer of ± 2 by ± 45 ° , and a source follower-type amplifier that synthesizes an output signal of the phase shifter and outputs an intermediate frequency signal. I have. Thereby, while suppressing the image signal ,
There is an effect that a high level intermediate frequency signal can be obtained. According to the second aspect, since the phase shift distributor and the phase shifter are each configured by the resistor and the capacitor having the same value, the gain error and the phase error due to the fluctuation of these values are canceled, and the error is reduced. There is an effect that the image suppression ratio can be kept high without generation.

According to the third aspect of the present invention, since all the components of the image suppression mixer are formed on the same semiconductor substrate, the size can be reduced, and the values of the resistors and the capacitors can be made the same so that the manufacturing process can be performed. There is an effect that no error is caused by the variation in.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an image suppression mixer according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional image suppression mixer.

FIG. 3 is a characteristic diagram showing a relationship between a variation in a constant and a gain error and a phase error in the phase shift distributor 20 in FIG.

FIG. 4 is a characteristic diagram showing a relationship between a variation in a constant and a gain error and a phase error in the phase shifter 40 in FIG.

FIG. 5 is a configuration diagram of an image suppression mixer according to a second embodiment of the present invention.

[Explanation of symbols]

10-phase distributor 20 phase distributor 21,24,42,43 resistance 22,23,41,44 capacitors 30 _1, 30 ₂ units mixer 40 phase shifter 50 differential amplifier 60 amplifier

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H03D 7/18

Claims (3)

(57) [Claims] An in-phase distributor that distributes a first high-frequency input signal to two systems and outputs first and second in-phase signals having the same level and phase, and a second high-frequency input signal into two systems. The first phase-shifted signal and the second phase-shifted signal have the same level and a phase of 90
A phase-shift distributor that outputs a second delayed phase-shifted signal; a first unit mixer that mixes the first in-phase signal and the first phase-shifted signal to generate a first mixed signal A second unit mixer that mixes the second in-phase signal and the second phase- shifted signal to generate a second mixed signal; and a second unit mixer whose phase is delayed by 45 ° from the first mixed signal. 1 and generates a phase signal from the second mixed signal.
Phase differs 180 ° with but of 45 ° advances the phase shifter first intermediate signal and level to produce a second intermediate signal that is equal, the first and second intermediate signals
Components, and in-phase components are synthesized and amplified.
An image suppression mixer comprising: a source follower-type amplifier that outputs an inter-frequency signal . Wherein said phase splitter, a first integration times composed of the first resistor and a first capacitor
A second resistor having a resistance equal to the first resistor;
And has a capacitance equal to the first capacitor
And a first differentiating circuit comprising a second capacitor.
The phase shifter is connected to a second integrating circuit comprising a third resistor and a third capacitor.
A fourth resistor having a resistance equal to the third resistor;
And has a capacitance equal to the third capacitor
2. An image suppression mixer according to claim 1, wherein said mixer comprises a second differentiating circuit comprising a fourth capacitor . 3. The in- phase distributor, the phase-shift distributor,
The first and second unit mixers, the phase shifter,
3. The image suppression mixer according to claim 1 , wherein the amplifier and the amplifier are formed on the same semiconductor substrate .