JP2001177425A - Radio receiver having image cancel mixer circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely eliminate an image signal by correcting a phase offset and a gain offset generated in an image cancel mixer circuit of an FM stereo receiver. SOLUTION: The image cancel mixer circuit consists of mixers 31, 32, and 33, a 1st phase shifter 34, and a 2nd phase shifter 35. The 1st phase shifter 34 uses two APF 3, 4 whose phase shift is fixed to form 90-degree phase shift, while the 2nd phase shifter 35 uses an APF1 whose phase shift is fixed and an APF2 whose phase shift is adjustable to form a phase shift. The phase of the AFP2 is variable by controlling e.g. a variable capacitor Cv. In the case of correcting the phase offset produced in response to the received frequency, the capacitance of the variable capacitor Cv is controlled in response to a tuning voltage of a channel selection circuit 14. The APF2 shifts the phase depending on the tuning voltage and the mixer 33 eliminates an image signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superheterodyne radio receiver having an image cancel mixer circuit in an FM tuner, and more particularly, to correcting a phase shift and a gain shift occurring in an image cancel mixer circuit to prevent image interference. The present invention relates to a radio receiver configured to remove the noise.

[0002]

2. Description of the Related Art Generally, a superheterodyne F
In an M stereo radio tuner, a local oscillation signal is mixed with a high-frequency signal to be received by a mixer circuit, and converted into an intermediate frequency signal. With respect to this application example, for example, a circuit configuration of a conventionally used FM stereo receiver will be described with reference to FIG.

The FM stereo receiver comprises an antenna 1, a high-frequency amplifier 2, a mixing circuit (mixer circuit) 3, an intermediate frequency amplifier 4, an amplitude limiting circuit 5, an FM detection circuit 6, a stereo demodulation circuit 7, de-emphasis circuits 8 and 9. , Low-frequency amplifiers 10 and 11, and speakers 12 and 13. Here, a right channel is formed by the de-emphasis circuit 8, the low-frequency amplifier 10, and the speaker 12, and a left channel is formed by the de-emphasis circuit 9, the low-frequency amplifier 11, and the speaker 13.

In order to select a desired FM broadcasting station, a frequency is selected in the high frequency amplifier 2 by a tuning voltage output from a tuning circuit 14. Then, in order to convert a high-frequency signal corresponding to this frequency selection into an intermediate frequency signal, this high-frequency signal is
The signal is mixed with the local oscillation signal from the local oscillation circuit 15 and converted into an intermediate frequency signal. Since the local oscillation signal must correspond to the frequency of the selected high-frequency signal,
The frequency of the local oscillation circuit 15 is also changed by the tuning voltage from the tuning circuit 14.

As described above, in the FM stereo receiver, a desired broadcast station can be selected and a broadcast program can be listened to through the speakers 12 and 13. However, in the mixer 3, a high frequency signal and a local oscillation signal are mixed. Since an intermediate frequency signal is obtained as a result, an image frequency is generated, causing interference with other broadcasting stations. The reason for this interference will be described with reference to FIG.

Now, when a received signal of frequency f ₁ is received from a desired broadcasting station, the frequency f ₀ of the local oscillation signal is supplied to the mixer 3 in order to output the frequency f _i of the intermediate frequency signal. Then, the reception frequency f ₁ , the local oscillation frequency f _0, and the intermediate frequency f _i have a relationship of f ₀ = f ₁ + f _i . At this time, as shown in FIG. 2, on the opposite side, the intermediate frequency f _i apart image signal of frequency f ₂ from the local oscillation frequency f ₀ is generated as the reception frequency f ₁ with respect to the local oscillation frequency f ₀ . Here, the airwaves of another broadcasting station in the image frequency f ₂ is present, it causes a beat between the frequency f ₂ and the local oscillation frequency f _0, to generate a frequency f ₂ -f _0. Where the frequency f ₂ −f ₀
Is equal to the intermediate frequency f _i , so in the receiver:
Interference occurs between a desired broadcasting station and another broadcasting station, resulting in so-called image disturbance. In the case of the upper heterodyne system, f _i = f ₀ −f ₁ = f ₂ −f ₀
Next, a _{f 2 = f 1 + 2 ×} f i.

Until now, a system using a narrow band filter such as a ceramic filter has been mainly used in order to remove the image disturbance. However, in order to reduce cost, image interference has been removed without using such a filter. Therefore, an image cancel mixer circuit that can completely cancel the image frequency in theory is used in the fields of television tuners, satellite broadcast receivers, and communication devices.

An example of an image canceling mixer used for these will be described with reference to FIG. The image cancel mixer includes a first mixer 31, a second mixer 32, a third mixer 33, a first phase shifter 34, and a second phase shifter 3.
5, and a low-pass filter 36. The phase shift amounts of the first phase shifter 34 and the second phase shifter 35 are both π / 2.
It is. And to be able to enter the local oscillation signal L _i, the high-frequency signal H _i is input, the intermediate frequency signal I ₀
Is output.

Next, the image cancellation function shown in FIG.
The principle by which the image signal can be removed by the
You. Here, the high frequency signal H_iAnd the image signal S
Each, H_i= E₁× sin ω₁t S = E_Two× sin ω_Twot. Also, the intermediate frequency signal I₀The angular frequency of_iToss
Then, the angular frequency ω of the image signal S_TwoIs the frequency
From the relation of numbers, ω_Two= Ω₁+ 2 × ω_i Becomes Further, the local oscillation signal L_i, L_i= E_Three× sin ω_ThreeAssuming that t, the light passes through the second phase shifter 35 to the second mixer 32.
When the input local oscillation signal is L₀, L₀= E_Four× cosω_Fourt. Note that the amplitude and phase shift of the second phase shifter 35 vary.
E without the key _Three= E_Four, Ω_Three= Ω_FourAnd

Therefore, only the phase relationship between the signals is examined.
I will do it. The first mixer 31 and the first phase shifter 34
As the output after passing, the received high-frequency signal H_i Nitsu
And -1 / 2 × sin ω_iIs about the image signal S.
And -1 / 2 × sin ω_iAre respectively output. Soshi
After passing through the second phase shifter 35 and the second mixer 32
As an output, the received high frequency signal H_iAbout -1 /
2 × sin ω_iIs １ ／ ×× for the image signal S.
sinω_iAre respectively output. Where ω _iBeyond
Frequency components are removed by the low-pass filter 36.
Shall be

Here, assuming that the third mixer 33 is an adder, the high-frequency signal H
_{For i} , −１ ／ × sin ω _i −１ ／ × sin ω _i = −sin
omega _i is, and for the image signal _{S, -1 / 2 × sinω i} + 1/2 × sinω i = 0 is output.

Thus, it can be seen that the image signal can be removed with the configuration of the image cancel mixer circuit shown in FIG.

[0013]

As described above, when only the phase relationship of each signal is considered, the image signal can be removed in principle in the image cancel mixer circuit shown in FIG. However, in practice, the first phase shifter 34 and the second phase shifter have variations in the amount of phase shift and the gain, so that the amount of removal of the image signal is reduced. Further, the first mixer 31, the second mixer 32 and the third mixer
Even in the mixer 33 and the low-pass filter 36, there are variations in the phase and the gain, which affects the image signal removal.

[0014] These phase shifters and mixers are susceptible to the effects of external environment, for example, fluctuations in ambient temperature and power supply, and their phases and gains fluctuate. Therefore, these phase and gain fluctuations also affect image signal rejection. Thus, for example, in the case of FM broadcasting, it is necessary to suppress the phase shift and the gain variation even within the range of the maximum frequency transition (± 75 kHz).
Further, it is necessary to suppress the phase shift and the gain variation even if the reception frequency changes in a wide range of the broadcast frequency of FM broadcast from 76 to 90 MHz. Further, for example, even when there is an environmental change such as a temperature condition or a power supply fluctuation as in an FM receiver mounted on an automobile, it is necessary to suppress phase shift and gain variation.

According to the present invention, there is provided an image cancel mixer circuit which suppresses a phase shift and a gain variation which affect removal of an image signal from a received high-frequency signal.

[0016]

Therefore, in order to solve the above-mentioned problems, at least a high-frequency amplifier, a tuning circuit, a local oscillation circuit, and reception from the high-frequency amplifier selected by the tuning circuit. A first mixer for mixing the received high-frequency signal and the local oscillation signal in a radio receiver having an image cancel mixer circuit for mixing a high-frequency signal and a local oscillation signal from the local oscillation circuit and converting the mixed signal into an intermediate frequency signal And 90 from the local oscillation signal.
A second mixer that mixes the phase-shifted signal and the received high-frequency signal, and a third mixer that mixes the signal shifted by 90 ° from the first mixer and the signal from the second mixer.
The image cancellation mixer circuit including a mixer,
There is provided a phase adjusting means for correcting a phase shift occurring in the image cancel mixer circuit.

The phase adjusting means further includes a tuning voltage output from the tuning circuit and a detection voltage output from a temperature detection circuit for detecting a peripheral temperature of the image cancellation mixer circuit. ,
The phase can be changed based on a detection voltage from a power supply voltage detection circuit that detects a change in the power supply voltage. Further, the phase adjusting means can change the phase by an all-pass filter including a variable impedance or a plurality of switchable delay circuits having delay amounts different from each other.

The radio receiver further includes gain control means for correcting a gain shift in the image cancellation mixer circuit, and a temperature around the image cancellation mixer circuit based on a tuning voltage output from the tuning circuit. The gain can be changed based on the detection voltage output from the temperature detection circuit for detecting the fluctuation of the power supply voltage, and further based on the detection voltage from the power supply voltage detection circuit for detecting the fluctuation of the power supply voltage.

According to the present invention, even if a phase shift or a gain shift occurs in the image cancel mixer circuit,
The image signal can be reliably removed by being corrected by the phase adjusting means or the gain controlling means.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. An embodiment of an image cancel mixer circuit is a first embodiment in which the phase and the gain are corrected with a tuning voltage. The case where the phase and the gain are corrected by detecting the temperature as the second embodiment and the case where the phase and the gain are corrected by detecting the power supply voltage as the third embodiment will be described separately. [First Embodiment] An example in which an image cancel mixer circuit 3a capable of correcting a phase and a gain with a tuning voltage is applied instead of the mixer circuit 3 in the circuit configuration of the FM stereo receiver shown in FIG. As shown in FIG. 4, the same parts as those in FIG. 1 are denoted by the same reference numerals. However, the description after the amplitude limiting circuit 5 in the circuit configuration of the FM stereo receiver is omitted because there is no change.

The image canceling mixer circuit 3a is for the basic configuration of the image canceling mixer circuit shown in FIG. 3, mixing a local oscillation signal L _i from the local oscillation circuit 5 to the high-frequency signal H _i to be inputted Then, an intermediate frequency signal I _{0 from} which the image signal S has been removed is output. further,
In the image cancel mixer circuit 3a, a tuning voltage is supplied from the tuning circuit 14 in order to correct the phase shift and the gain shift, and the tuning voltage is also changed in accordance with the tuning in the high frequency amplifier circuit 2. And applied.

Here, means for correcting a phase shift in the first embodiment will be described. For example, FIG.
As shown in (a), FM broadcasts in Japan are allocated with reception frequencies ranging from 76 MHz to 90 MHz. At this time, the local oscillation circuit 15 is controlled by the tuning circuit 14 with the tuning voltage, and the local oscillation signal _Li is supplied to the image cancel mixer circuit 3. When the local oscillation signal _Li is changed along with the tuning, the phase shifter 35 of the mixer circuit shown in FIG. 3 outputs a 90-degree phase shift output as shown by a curve A in FIG. However, the phase shifts depending on each tuning frequency.

This means that the image signal cannot be removed as described above. This curve A must be flat with respect to the reception frequency to provide a stable 90-degree phase shift output. As a countermeasure, an all-pass filter (APF) shown in FIG.

This APF has the required frequency:
This is a filter that can maintain the magnitude of the voltage of the input signal as it is, and change and output only the phase. AP
In F, it is possible to output only by changing the phase.
This will be described with reference to FIG. The basic circuit of APF is O
It is constituted by an AMP of a P amplifier, two resistors R, a first impedance 51 and a second impedance 52. An input signal e _i is input to the negative terminal of AMP via a resistor R. Further, a first impedance 51 is connected to the positive terminal (+) of the AMP, and the input signal e _i
It is input via an impedance 52. And AM
A resistor R is connected between the negative terminal (-) of P and the output terminal _eo, and the input resistance R and the feedback resistance R of the AMP are equal.

Here, a description will be given of the fact that the APF configured as described above can maintain the magnitude of the voltage of the input signal as it is and output the signal while changing only the phase. The impedance of the first impedance 51 is Z ₁ , and the impedance of the second impedance 52 is Z ₂ . Then,
The relationship between the input signal e _i and the output terminal e _o is as follows: e _o = e _i (Z ₁ −Z ₂ ) / (Z ₁ + Z ₂ ). Now, Z ₁ = ₁ / _jωC, When _{Z 2 = R, e o =} e i (1-jωC) / a (1 + jωC). Therefore, regarding the gain, | e _o | = | e _i | × {1 ² + (ωCR) ² } ^1/2 / ｛1
Expressed by ^{2 + (ωCR) 2} 1/2} , | e o | = | e i | from become possible, irrespective of the frequency, the gain is constant ones.

Next, regarding the phase, if the phase is θ, it can be expressed as θ = −tan ⁻¹ × 2ωCR / {1− (ωCR) ² }, whereby the capacitance C or the resistance R can be changed. Thus, it can be seen that the phase can be changed. The maximum phase rotation of such a primary filter is 180 degrees,
Next, it becomes 360 degrees.

Although the magnitudes of the input resistance and the feedback resistance of the AMP are equal, if these resistances are different, the gain of the APF with respect to the frequency can be changed. Based on such a principle, in the APF shown in FIG.
Impedance Z ₁ of the first impedance 51, by adjusting the impedance Z ₂ of the second impedance 52 as appropriate, it maintains the magnitude of the voltage of the input signal can change the phase by. By incorporating this APF into the phase shifter, the change in the phase with respect to the reception frequency changes from the curve A shown in FIG. 6A to the curve B shown in FIG. 6B. , Can be adjusted to a flat one.

Next, a description will be given of a phase changing means of the APF when the APF is incorporated in the phase shifter. As described above, in order to change the phase of the APF, the impedance Z ₁ of the first impedance 51 and the second impedance 5
What is necessary is just to be able to select the impedance Z2 of ₂ . As the phase changing means in FIG. 7, an example of using a capacitive impedance Z _1.

Here, as means for changing the magnitude of the impedance Z _1, a plurality of capacitors C _{2 to} C _n having a fixed capacity are prepared, and each capacitor is connected between the positive terminal of the AMP and the ground. A set of switches SW is formed in series, and these sets are connected in parallel. Then, a switch SW ₁ through the changeover switch control circuit 16 for controlling the on-off SW _m. The selector switch control circuit 16 is supplied with the tuning voltage from the tuning circuit 14, in response to the tuning voltage, such that the magnitude of the impedance Z ₁ is changed, switching control switches SW ₁ to SW _m I do.

In this example, a plurality of capacitors C ₂
Or is a C _n are switched in multiple switches SW ₁ to SW _m, instead of these capacitors and switches,
Even if a variable capacitor such as a varicap capable of changing the size of the capacitor according to the tuning voltage is used, the same function can be obtained. In this case, the changeover switch control circuit 16 may output a voltage corresponding to the tuning voltage, or the capacitance may be controlled directly or by adjusting the tuning voltage.

In the example shown in FIG. 7, the case where a capacitor is used for the APF has been described. FIG. 8 shows an example in which a plurality of resistors are used. However, the impedance Z _1, using the capacitor C, the size of the capacitor C is a fixed value. It will be described means for changing the magnitude of the impedance Z _2. As means for changing the magnitude of the impedance Z _2, a plurality of resistors R ₂ to R _n of a plurality of switches SW ₁ to SW _m, respectively connected to from a series of pairs, in the parallel those set respectively , connected between the positive terminal and the input terminal e _i of AMP. These switches SW ₁ to SW _m, as in the example of FIG. 7, is controlled by switching the switch control circuit 16. Then, in response to the tuning voltage, such that the magnitude of the impedance Z ₂ is changed to the switching control of the switch SW ₁ to SW _m.

Although the case where the magnitude of the impedance Z ₂ is changed by a set of a resistor and a switch has been described above, a variable resistor is used as the impedance Z ₂ instead of a plurality of sets of a resistor and a switch. Can also. In this case, a voltage corresponding to the tuning voltage may be output from the changeover switch control circuit 16, or the variable resistor may be controlled directly or by adjusting the tuning voltage.

The phase shift is corrected by using the APF.
Therefore, in FIG. ₁The size of
In FIG. 8, the impedance Z_TwoChange the size of each
Has been described, but the
-Dance Z₁And impedance Z_TwoChange the size of both
You may make it change. In the above, the phase of the APF is changed.
As a further means, the impedance of the first impedance 51 is
Dance Z₁, The impedance of the second impedance 52
Z_TwoTo control the size of each of the
Was explained using an example of the case where
APF is used as the detector and a predetermined 90 degree phase shift is performed.
Connected the means to correct the phase shift to the output side of APF
This case will be described with reference to FIG.

In the APF, the first impedance 51
Impedance Z₁The capacitor C as the second
Impedance Z of the impedance 52_TwoAs resistance R₁To
Select and keep the phase of the APF itself fixed. Soshi
In the output of the APF, the delay circuit and the switch
Connect multiple sets in parallel. These individual delay times
The path provides a fixed amount of delay to the input signal.
This delay shifts the phase of the input signal. one
Multiple delay circuits D for providing a fixed amount of delay₁Or D _nSo
Switch SW for each₁Or SW_nConnected in series, it
Connect each pair in parallel.

The switches SW _{1 to} SW _n are controlled by the changeover switch control circuit 16 in accordance with the tuning voltage. The signal input to the APF is input to each delay circuit after being phase-shifted by 90 degrees by the APF. Then, I switched a plurality of delay circuits D ₁ to D _n, are made to correct the phase shift centered on the 90 degrees.

Up to now, AP has been used to correct the phase shift.
Various means using F have been described.
Image cancel mixer circuit 3 of FM receiver shown in FIG.
A specific example of correcting the phase shift in a will be described with reference to FIG. The image cancel mixer circuit 3a shown in FIG. 10 is based on the configuration of the image cancel mixer circuit 3 shown in FIG. 3, and the same parts are denoted by the same reference numerals. However, the image cancel mixer circuit 3a
Is different from the image cancel mixer circuit 3 in the circuit configuration of the first phase shifter 34 and the second phase shifter 35.

In the mixer circuit 3, the first phase shifter 34 is
Although present between the mixer 31 and the third mixer 33,
In the mixer circuit 3a, the first mixer 31 and the third mixer 33
And the APFs 3 and 4 are inserted between the second mixer 32 and the third mixer 33, respectively, and these APFs cause a phase difference of 90 degrees between the output signals from the first mixer 31 and the second mixer 32. Is given. The circuit configuration of the APFs 3 and 4 is the same as that of the APF shown in FIG. 5, except that the first impedance 51 and the second impedance 52 are fixed values and the phase is shifted by 90 degrees.

Also in the second phase shifter 35, the mixer circuit 3a gives a phase difference of 90 degrees to the local oscillation signal from the local oscillator 15 supplied to the first mixer 31 and the second mixer. APF1 and APF2 are connected. The first mixer 31 is supplied with the output of APF1 and the second mixer 32 is supplied with the output of APF2. The circuit configuration of the APF 1 forming a part of the second phase shifter 35 is the same as that of the APF shown in FIG.
And the second impedance 52 is set to a fixed value so as to give a fixed phase shift amount to the local oscillation signal. The circuit configuration of the APF 2 constituting the other is similar to that of the APF shown in FIG.
2 can be changed.

In the specific example shown in FIG.
Variable impedance C with 1 impedance 51 _vAnd this
Variable capacitance C_vOf the capacitance obtained from the tuning circuit 14
It is controlled by the tuning voltage. As a result, in FIG.
As shown by the curve B in FIG.
to correct. The phase shift amount of the second phase shifter 35 is 90 degrees.
For example, when the reception frequency to be tuned becomes high,
Since the tuning voltage also increases, the variable capacitance C_vApplied to
And the capacitance value changes, and the APF2
Acts to delay the phase.

As described above, in the image cancel mixer circuit 3a, the first impedance of the APF is changed according to the tuning voltage, the phase shift with respect to the reception frequency is corrected, and the image signal is removed. as 2 phase shifter, with APF2 using the variable capacitance C _v in the first impedance, although the case where the phase adjustment, as APF2, as shown in FIG. 7, with APF for selecting a plurality of capacitors A phase shifter may be used. Alternatively, as shown in FIG. 8, a phase shifter using an APF in which the second impedance is a variable resistor may be used. Furthermore, APF
As shown in FIG. 9, the APF itself has a fixed phase as shown in FIG.
A means for adjusting the phase of the phase shifter by a plurality of delay circuits may be used.

In FIG. 10, the AP of the second phase shifter 35
Although the phase is adjusted by F2, the phase may be adjusted by APF1, or the phase may be adjusted by the first phase shifter 34 instead of the second phase shifter 35. Until now, the 90-degree phase formation in the second phase shifter 35, which is a part of the image cancel mixer circuit 3a, has been performed by the APF. Next, this phase formation is performed by the flip-flop to correct the phase shift. APF
Will be described with reference to FIG.

The FM receiver shown in FIG.
It is similar to the M receiver, and the same parts are denoted by the same reference numerals. However, the second phase shifter 35 shown in FIG. 11 performs the phase formation of 90 degrees by the flip-flops F ₁ and F ₂ ,
FIG. 10 shows that the APF is used to correct the phase shift.
Is different from Here, the flip-flop F ₁
And forming a 90 degree phase with F ₂ , FIG.
This will be described with reference to FIG. In this case, the local oscillator 15
The oscillation frequency of a is set to twice the oscillation frequency of the local oscillator 15 in FIG.

The oscillation signal of the local oscillator 15a is shown in FIG. When the flip-flops F ₁ and F ₂ are driven by rising and falling, and the oscillation frequency of the local oscillator 15 is _{１ ／} divided by the flip-flops F ₁ and F ₂ , a signal supplied to the first mixer 31 Figure 1
2B, the signal supplied to the second mixer 32 is 9 times smaller than the signal supplied to the first mixer 31.
A rectangular wave having a phase difference of 0 degrees is obtained, as shown in FIG. When both the flip-flops F ₁ and F ₂ are driven at the rising edge, the inverter INV may be inserted into one of the inputs.

The first mixer 31 and the second mixer 32
Even if the rectangular waves are supplied and mixed, the low-pass filter 36 can obtain a fundamental wave. An APF was combined with such a phase shifter using flip-flops F ₁ and F ₂ to form a second phase shifter 35 of an image cancel mixer circuit as shown in FIG.

In FIG. 11, a tuning voltage is supplied from the tuning circuit 14 using the variable capacitance C _v as the second impedance of the APF. Thereby, the capacitance is varied, and the second impedance is adjusted. By this adjustment, the duty ratio of the local oscillation signal can be controlled, and the phase shift can be corrected. When there is no phase shift, the duty ratio is 50%.

[0046] Further, in FIG. 11 shows the case of a phase shifter using the variable capacitance C _v in the second impedance APF, as the phase shifter, the phase shifter using a plurality of capacitors according to Figure 7 The phase shift can be corrected by replacing the phase shifter using a variable resistor shown in FIG. 8 or the phase shifter using a plurality of delay circuits shown in FIG. next,
In each of the first phase shifter 34 and the second phase shifter 35 constituting a part of the image cancel mixer circuit in the FM receiver, a plurality of delay circuits are selected based on the tuning voltage, and a phase difference of 90 degrees is selected. While forming
A specific example in which the phase shift can be corrected will be described.

FIG. 13 shows a case in which selecting a plurality of delay circuits incorporates an image cancel mixer circuit into an FM receiver. As the first phase shifter 34, between the first mixer 31 and the third mixer 33, a plurality of pairs of connecting the switch SW ₁₁ to SW _1n in series to each of the delay circuits D ₁₁ to D _1n in parallel The circuit configuration was inserted.
Then, Similarly, the second phase shifter, delay circuit D ₂₁ through D
Circuits composed of _2n and the switch SW ₂₁ to SW _2n.

The first phase shifter 34 has a delay circuit D ₁₁ having a delay amount slightly shifted from the phase of 90 degrees.
To D _1n , the phase shifter as a whole performs a phase shift of 90 degrees, and the second phase shifter 35 also has a delay circuit D ₁₁ having a delay amount slightly shifted from the phase of 90 degrees.
To D _1n , and the phase shifter performs 90 ° phase shift as a whole.

The control of the switch SW ₁₁ to SW _1n and the switch SW ₂₁ to SW _2n connected in series with each delay circuit is performed based on the tuning voltage obtained from the channel selection circuit 14. The tuning voltage is converted to a switch selection signal selector switch control circuit 16, this selection signal, the on-off switch SW ₁₁ to SW _1n and the switch SW ₂₁ to SW _2n are individually controlled. This control is selected the delay circuit D ₁₁ through D _1n and the delay circuit D ₂₁ through D _2n, it is possible to remove the image signal.

In the above, the image signal is removed by correcting the phase shift by adjusting the phase in the first phase shifter or the second phase shifter in the image cancel mixer circuit. Alternatively, a case will be described in which the phase of the second phase shifter is fixed to 90 degrees, and a phase adjustment unit is inserted to correct the phase shift. FIG. 14 shows an image cancel mixer circuit in the FM receiver. The image cancel mixer circuit is the same as the basic circuit configuration of the mixer circuit shown in FIG. 3, and the same parts are denoted by the same reference numerals.

An APF whose phase can be adjusted is inserted between the second mixer 32 and the third mixer 33. In FIG. 14, A
A first impedance Z ₁ of the PF shows the case of a variable capacitance C _v. Based on the tuning voltage obtained from the channel selection circuit 14, by controlling the variable capacitor C _v, to correct the deviation was phase in accordance with the reception frequency. In FIG. 14, a first impedance Z ₁ variable capacitance C
_v , but APF for selecting multiple capacitors in FIG.
However, the APF using the variable resistor shown in FIG. 8 may be used.

FIG. 15 shows an image cancellation mixer circuit using a plurality of delay circuits having different selectable delay amounts shown in FIG. Delay circuits D _{1 to} D _n having different delay amounts are arranged between the first phase shifter 34 and the third mixer 33 so as to be selectively inserted. A tuning voltage is supplied from the tuning circuit 14 to the changeover switch control circuit 16, and the changeover switch control circuit 16 changes the switches SW ₁ to SW in accordance with this voltage.
Controls on / off of _n . ON / OFF of these switches
By turning off, the phase of the output signal of the first phase shifter 34 is adjusted, and the phase shift is corrected.

Although the delay circuits D _{1 to} D _n having different delay amounts are inserted between the first phase shifter 34 and the third mixer 33, the delay circuits D _{1 to} D _n are connected between the second mixer 32 and the third mixer 33. May be inserted. Further, in FIG. 15, the switch SW ₁ through SW _n is turned on and off individually controlled, the control output line from the selector switch control circuit 16 is a plurality, illustrated with simplified description of the drawings.

The specific examples described so far have shown correction of a phase shift based on a tuning voltage in an image cancel mixer circuit. Next, a specific example of correcting a gain deviation based on a tuning voltage in a case where an image signal cannot be removed due to a deviation in the gain in the image cancellation mixer circuit will be described.

FIG. 16 shows an image cancel mixer circuit in the FM receiver. The basic circuit configuration of this image cancel mixer circuit is the same as that of the image cancel mixer circuit shown in FIG. The sign was attached. A gain control circuit G ₁ is provided in the first mixer 31, and a variable resistor R _v for controlling the gain of the gain control circuit G ₁ is connected. Here, the gain control circuit G
₁ may be constituted by an FET or the like, and the gain may be controlled by changing its bias voltage with a variable resistor _Rv .

[0056] Then, by supplying a voltage based on the tuning voltage obtained from tuning circuit 14 to the variable resistor R _v, by changing the resistance value for controlling the gain control circuit G _1. Therefore,
The gain deviation between the two signals input to the third mixer 33 is corrected. Although FIG. 16 shows the case where the first mixer 31 is provided with a gain control circuit, the second mixer 32 may be provided with a gain control circuit, and it is sufficient if the gain control circuit is provided in one of the mixers.

[0057] In FIG. 16, but with a gain control circuit G ₁ inside the mixer, 17, the second mixer 32 and the third
An illustrative example of inserting the gain control circuit G ₂ between the mixer 33. The basic circuit configuration of the image cancel mixer circuit is the same as in FIG. 16, and the same parts are denoted by the same reference numerals. The gain control circuit G ₂ is also a variable resistor R _v is connected, a variable resistor R _v voltage supply based on the tuning voltage obtained from tuning circuit 14 to, by changing the resistance value the gain control circuit G ₂ Control. Therefore, the third mixer 33
To correct the gain shift between the two signals input to the.

In the above, specific examples of various means for correcting the phase shift or the gain shift in the image cancel mixer circuit based on the tuning voltage have been described, and the control for removing the image signal has been described. The image signal may be removed by combining the means for correcting the phase shift or the means for correcting the gain shift according to the cause of the generation of.

As shown in FIG. 14, when an APF is inserted between the mixers to correct the phase shift, A
In PF, replacing the feedback resistance R _a of the AMP to the variable resistor R _v, the voltage may be supplied to based on the tuning voltage. Then, as mentioned above, AP
Although the gain is not constant, which is a feature of F, A
By controlling the gain of the PF, not only can a gain shift be corrected, but also a phase shift can be corrected. [Second Embodiment] In the first embodiment, the embodiment of the image cancellation mixer circuit has been described in which the phase and the gain are corrected by the tuning voltage. However, in the second embodiment, the ambient temperature of the mixer circuit is corrected. In the case of detecting the phase and correcting the phase and the gain, various specific examples will be described with reference to FIGS.

An example in which, instead of the mixer circuit 3 in the circuit configuration of the FM stereo receiver shown in FIG. 1, an image cancel mixer circuit 3b capable of correcting the phase and the gain with a voltage corresponding to the detected ambient temperature is applied. Is shown in FIG. In FIG. 18, the same parts as in FIG.
The same reference numerals are given. However, the description after the amplitude limiting circuit 5 in the circuit configuration of the FM stereo receiver is omitted because there is no change.

[0061] image canceling mixer circuit 3b is for the basic configuration of the image canceling mixer circuit shown in FIG. 3, mixing a local oscillation signal L _i from the local oscillation circuit 5 to the high-frequency signal H _i to be inputted Then, an intermediate frequency signal I _{0 from} which the image signal S has been removed is output. further,
In the image cancel mixer circuit 3b, a voltage that changes according to the ambient temperature is supplied from the temperature detection circuit 17 in order to correct the phase shift and the gain shift.

In FIG. 18, the tuning voltage from the tuning circuit 14 is also supplied to the image cancel mixer circuit 3b along with the tuning in the high frequency amplifier circuit 2, and the phase shift and the gain shift according to the reception frequency are corrected. I can do it. In the image cancellation mixer circuit 3b, the phase shift and the gain shift with respect to the reception frequency may be corrected together with the phase shift and the gain shift with respect to the fluctuation of the ambient temperature. By the way, FIGS. 19 to 25
Hereinafter, for simplicity, the following description will focus on the means for correcting the phase shift and the gain shift with respect to the fluctuation of the ambient temperature.

Since the image cancel mixer circuit 3b, the local oscillation circuit 15 and the like are usually composed of semiconductor elements, they are easily affected by the ambient temperature, and the operating points of the respective circuits fluctuate due to the ambient temperature. become. And
Variations also exist between elements constituting a circuit. A difference occurs in the output characteristics between mixers having the same circuit configuration or between phase shifters. This means that the image signal cannot be removed by the image cancel mixer circuit shown in FIG. Therefore, the ambient temperature is detected, and the phase shift and the gain shift are corrected according to the detected voltage.

The image cancel mixer circuit in the FM receiver shown in FIG. 19 uses the image cancel mixer circuit shown in FIG. 10 and has the same circuit configuration. In the specific example shown in FIG. 19, the phase shift is corrected by the detection voltage corresponding to the ambient temperature.
The same parts as those in FIG. 10 are denoted by the same reference numerals. The image cancel mixer circuit includes a temperature detection circuit 17. The temperature detecting circuit 17 is installed near the image cancel mixer circuit, detects a temperature near the image cancel mixer circuit, and outputs a detection voltage corresponding to this temperature.

[0065] Then, the detection voltage from the temperature detection circuit 17 is supplied to the variable capacitance C _v of APF2 in the second phase shifter 35. Variable capacitance C _v is the capacitance value is changed by the detected voltage, as described above, the phase of APF2 is adjusted. Then, the local oscillation signal whose phase has been adjusted is supplied to the second mixer 32. In response to temperature variations, so that the image signal in the third mixer 33 is phase-adjusted so canceled, it is sufficient to set the capacitance value of the variable capacitance C _v.

FIG. 19 shows an example in which the variable capacitance _Cv is used for the first impedance of the APF. However, the APF for selecting a plurality of capacitors shown in FIG. 7 may be used. A that makes the second impedance variable
It may be PF. Further, as shown in FIG.
A plurality of delay circuits D _{1 to} D _n are connected to a plurality of switches SW.
By selecting _one or SW _n, it may be phase adjusted.

Next, the image cancel mixer circuit in the FM receiver shown in FIG. 20 is based on forming a 90 ° phase difference by dividing a local oscillation signal by １ ／ with a flip-flop. Yes, it uses a circuit configuration similar to that of the image cancel mixer circuit shown in FIG. In the specific example shown in FIG. 20, the phase shift is to be corrected by the detection voltage corresponding to the ambient temperature, and the same parts as those in FIG. 11 are denoted by the same reference numerals.

In the image cancel mixer circuit in the FM receiver shown in FIG. 20, the detection voltage from the temperature detection circuit 17 is the variable capacitance C _v which is the first impedance of the APF, as in the specific example shown in FIG. Supplied to
Depending on the voltage, the capacitance value of the variable capacitance C _v is to change, APF phase is controlled. By this phase adjustment, the duty ratio is controlled, and the phase shift of the mixer circuit affected by the ambient temperature can be corrected.

In the phase adjustment shown in FIG. 20, the variable capacitance C
_Although an APF having _v is used, a phase shifter using a plurality of capacitors according to FIG. 7, a phase shifter using a variable resistor according to FIG. 8, or a phase shifter using a plurality of delay circuits according to FIG. Even if it is replaced, the phase shift can be corrected.
Next, the image cancellation mixer circuit in the FM receiver shown in FIG. 21 uses a circuit configuration similar to that of the specific example shown in FIG. The phase shift is corrected by selecting a circuit with a switch. In FIG. 21, the same parts as those in FIG. 13 are denoted by the same reference numerals.

The difference between the image cancel mixer circuit shown in FIG. 21 and the mixer circuit shown in FIG.
The control voltage input to the changeover switch control circuit 16 is not a tuning voltage but an output voltage from the temperature detection circuit 17. The temperature detection circuit 17 detects the temperature around the mixer circuit, and controls the changeover switch control circuit 16 according to the detected voltage. Then, in response to the detected voltage, respectively selectively turn on and off the switch SW ₁₁ to SW _1n and the switch SW ₂₁ to SW _2n of the second phase shifter 35 of the first phase shifter 34. ON / OFF of these switches
The off-delay circuit D ₁₁ through D _1n and the delay circuit D ₂₁ through D _2n of the second phase shifter 35 of the first phase shifter 34 is selected, it is possible to correct the phase shift.

FIG. 22 shows an FM receiver.
Although the image cancel mixer circuit is shown,
The cell mixer circuit is a basic circuit of the mixer circuit shown in FIG.
It is the same as the road configuration, and the same parts are denoted by the same reference numerals.
Phase adjustment between the second mixer 32 and the third mixer 33
APF was inserted. In FIG. 22, the first in
Peedance Z₁Is the variable capacity C_vShows the case
You. Based on the detection voltage obtained from the temperature detection circuit 17
And this variable capacitance C _vBy controlling the mixer times
The phase shift due to the temperature fluctuation generated in the road is corrected.

In FIG. 22, the first impedance Z
_{Although the} variable capacitance _Cv is set to ₁ in FIG. 8, the APF for selecting a plurality of capacitors shown in FIG.
F or a plurality of selectable delay circuits as shown in FIG. Further, in FIG. 23, according to the ambient temperature, different amount of delay to select a plurality of delay circuits D ₁ to D _n having shows an image cancel mixer circuit for correcting the phase shift. The image cancel mixer circuit shown in FIG. 23 is the same as the image cancel mixer circuit shown in FIG. 15, and the same parts are denoted by the same reference numerals.

In the image cancel mixer circuit shown in FIG. 23, the control voltage input to the changeover switch control circuit 16 is not the tuning voltage but the output voltage from the temperature detection circuit 17. The temperature detection circuit 17 detects the temperature around the mixer circuit, and according to the detected voltage,
The changeover switch control circuit 16 is controlled. Then, in response to the detected voltage, are selectively turning on and off the switch SW ₁ to SW _n. These switches on and off, it is possible to delay circuit D ₁ to D _n is inserted between the first phase shifter 34 and the third mixer 33 is selected to correct the phase shift.

In FIG. 23, a plurality of delay circuits D
₁ has been inserted to D _n between the first phase shifter 34 and the third mixer 33, may be inserted between the second mixer 32 and the third mixer 33. The specific examples described so far show that the image shift mixer circuit corrects the phase shift based on the detected voltage at which the ambient temperature is detected.

Next, in the case where the image signal cannot be removed due to a shift in the gain due to a change in the ambient temperature in the image cancel mixer circuit, the shift in the gain is corrected based on the detected voltage at which the ambient temperature is detected. An example will be described. FIG. 24 shows an image cancel mixer circuit in the FM receiver. The basic circuit configuration of this image cancel mixer circuit is the same as that of the image cancel mixer circuit shown in FIG. 16, and the same parts are denoted by the same reference numerals. did.

A gain control circuit G ₁ is provided in the first mixer 31, and a variable resistor R _v such as an FET is connected to control the gain of the gain control circuit G ₁ . Then, supplying a detection voltage obtained from the variable resistor R _v temperature detection circuit 17, the change of the resistance value for controlling the gain control circuit G _1. Therefore, the gain deviation between the two signals input to the third mixer 33 is corrected.

FIG. 24 shows the case where the first mixer 31 is provided with a gain control circuit. However, the second mixer 32 may be provided with a gain control circuit. Good. Further, in FIG. 24, the case with a gain control circuit G ₁ inside the mixer, in FIG. 25, the second
Gain control circuit G ₂ between mixer 32 and third mixer 33
Is shown. The basic circuit configuration of the image cancel mixer circuit is the same as that of FIG. 17, and the same parts are denoted by the same reference numerals.

[0078] The gain control circuit G ₂ is also a variable resistor R _v is connected and supplies a detection voltage obtained from the variable resistor R _v temperature detection circuit 17, the change of the resistance value of the gain control circuit G ₂ Control. Therefore, the gain deviation due to the temperature fluctuation of the two signals input to the third mixer 33 is corrected. As described above, specific examples of various means for correcting the phase shift or the gain shift in the image cancel mixer circuit based on the detection voltage that has detected the ambient temperature have been described, and the control to remove the image signal has been described. The image signal may be removed by combining a means for correcting a phase shift or a means for correcting a gain shift according to the generation cause of the image signal.

As shown in FIG. 22, when an APF is inserted between the mixers to correct the phase shift, A
In PF, replacing the feedback resistance R _a of the AMP to the variable resistor R _v, the detection voltage detected ambient temperature may be supplied. By controlling the gain of the APF, not only can a gain shift be corrected, but also a phase shift can be corrected. [Third Embodiment] In the image cancellation mixer circuit, in the second embodiment, the case where the phase and the gain are corrected by the detection voltage obtained by detecting the ambient temperature has been described. Various specific examples of the case where the voltage of the supplied power is detected and the phase shift and the gain shift caused by the fluctuation of the power supply voltage are corrected will be described with reference to FIGS.

An example in which, instead of the mixer circuit 3 in the circuit configuration of the FM stereo receiver shown in FIG. 18, an image cancel mixer circuit 3c capable of correcting a phase shift and a gain shift with a voltage detected from a power supply voltage is applied. To
As shown in FIG. 26, the same parts as those in FIG. 18 are denoted by the same reference numerals. However, the description after the amplitude limiting circuit 5 in the circuit configuration of the FM stereo receiver is omitted because there is no change.

[0081] image canceling mixer circuit 3c is for the basic configuration of the image canceling mixer circuit shown in FIG. 3, mixing a local oscillation signal L _i from the local oscillation circuit 5 to the high-frequency signal H _i to be inputted Then, an intermediate frequency signal I _{0 from} which the image signal S has been removed is output. further,
In the image cancel mixer circuit 3c, in order to correct the phase shift and the gain shift, the power supply voltage detecting circuit 18
A change in the power supply voltage is detected, and a voltage corresponding to the change is generated.

In FIG. 26, in addition to correcting a phase shift and a gain shift due to a power supply voltage fluctuation by supplying a voltage detected as a change in the power supply voltage, a tuning is performed in accordance with the tuning in the high frequency amplifier circuit 2. The tuning voltage from the circuit 14 is also supplied to the image cancel mixer circuit 3c, so that the phase shift and the gain shift according to the reception frequency can be corrected. Further, the image cancellation mixer circuit 3c is also provided with a temperature detection circuit 17, and may also correct a phase shift and a gain shift due to a change in ambient temperature. By the way, the specific examples shown in FIGS. 27 to 33 will be described below mainly on the means for correcting the phase shift and the gain shift due to the power supply voltage fluctuation for the sake of simplicity.

The image cancel mixer circuit 3c, the local oscillation circuit 15 and the like are connected to a power supply for driving each circuit. However, for example, in an FM stereo receiver mounted on an automobile, the battery voltage tends to fluctuate, which may affect the power supply of the FM stereo receiver or the like. Then, the power supply voltage of each circuit in the FM stereo receiver or the like fluctuates. Therefore, a phase shift and a gain shift occur in the image cancel mixer circuit 3c, the local oscillation circuit 15, and the like, and the image signal cannot be removed.

Therefore, a change in the power supply voltage is detected, and the phase shift and the gain shift are corrected according to the detected voltage. The image cancel mixer circuit in the FM receiver shown in FIG. 27 uses the same circuit configuration using the image cancel mixer circuit shown in FIG. In the specific example shown in FIG. 27, the phase shift is corrected by the detection voltage corresponding to the change in the power supply voltage, and the same parts as those in FIG. 19 are denoted by the same reference numerals.

The power supply voltage detection circuit 18 is provided in the image cancellation mixer circuit. The power supply voltage detection circuit 18 detects a change in the power supply voltage and outputs the detected voltage. Then, the detected voltage, and supplies to the variable capacitance C _v of APF2 in the second phase shifter 35. Variable capacitance C
_{As for v} , the capacitance value is changed by the detection voltage, and the phase of APF2 is adjusted as described above. Then,
The phase-adjusted local oscillation signal is supplied to the second mixer 32.

The capacitance value of the variable capacitor _Cv may be controlled so that the phase is adjusted according to the power supply fluctuation and the third mixer 33 cancels the image signal. FIG. 27 shows an example in which the variable capacitance _Cv is used for the first impedance of the APF. However, the APF for selecting a plurality of capacitors shown in FIG. 7 may be used. An APF that changes the second impedance may be used. Furthermore, as shown in FIG. 9, by selecting a plurality of delay circuits D ₁ to D _n in the plurality of switches SW ₁ to SW _n, may be phase adjusted.

Next, the image cancel mixer circuit in the FM receiver shown in FIG. 28 is based on forming a 90-degree phase difference by dividing a local oscillation signal by で with a flip-flop. Yes, it uses a circuit configuration similar to that of the image cancel mixer circuit shown in FIG. In the specific example shown in FIG. 28, the phase shift due to the power supply voltage fluctuation is corrected by the detected voltage that has detected the fluctuation of the power supply voltage, and the same parts as those in FIG. 20 are denoted by the same reference numerals.

In the image canceling mixer circuit in the FM receiver shown in FIG. 28, the detected voltage from the power supply voltage detecting circuit 18 is set to the AP as in the specific example shown in FIG.
Is supplied to the variable capacitance C _v is a first impedance F. Depending on the voltage, the capacitance value of the variable capacitance C _v is to change, APF phase is controlled. By this phase adjustment, the duty ratio is controlled, and the phase shift of the mixer circuit affected by the power supply voltage fluctuation can be corrected.

In the phase adjustment of FIG. 28, the variable capacitance C
_Although an APF having _v is used, a phase shifter using a plurality of capacitors according to FIG. 7, a phase shifter using a variable resistor according to FIG. 8, or a phase shifter using a plurality of delay circuits according to FIG. Even if it is replaced, the phase shift can be corrected.
Next, in the image cancel mixer circuit in the FM receiver shown in FIG. 29, using a circuit configuration similar to that of the specific example shown in FIG. The phase shift is corrected by selecting the delay circuit by a switch. FIG.
Then, the same parts as those in FIG. 21 are denoted by the same reference numerals. However, the image cancel mixer circuit of FIG.
The difference from the mixer circuit shown in (1) is that the control voltage input to the changeover switch control circuit 16 is not the voltage corresponding to the ambient temperature, but the output voltage from the power supply voltage detection circuit 18.

The power supply voltage detection circuit 18 detects the power supply voltage supplied to the mixer circuit, and according to the detected voltage,
The changeover switch control circuit 16 is controlled. Then, the switches SW _{11 to} S ₁₁ of the first phase shifter 34 correspond to the detected voltages.
W _1n and the switches SW _{21 to} SW _2n of the second phase shifter 35 are selectively turned on / off. By turning on and off these switches, the delay circuit D of the first phase shifter 34
_{11 to} D _1n and the delay circuits D _{21 to} D _{2n of} the second phase shifter 35 are selected, and the phase shift due to the power supply voltage fluctuation can be corrected.

Further, FIG. 30 shows an image cancel mixer circuit in the FM receiver. The image cancel mixer circuit has the same basic circuit configuration as the mixer circuit shown in FIG. Attached.
An APF whose phase can be adjusted is inserted between the second mixer 32 and the third mixer 33. In Figure 30, shows the case where the first impedance Z ₁ of the APF a variable capacitance C _v. Based on the detected voltage obtained from the power supply voltage detection circuit 18, by controlling the variable capacitor C _v, to correct the phase shift caused by source voltage fluctuation generated in the mixer circuit.

In FIG. 30, the first impedance Z
_{Although the} variable capacitance _Cv is set to ₁ in FIG. 8, the APF for selecting a plurality of capacitors shown in FIG.
F or a plurality of selectable delay circuits as shown in FIG. FIG. 31 shows an image cancel mixer circuit that selects a plurality of delay circuits D _{1 to} D _n having different delay amounts and corrects a phase shift due to power supply voltage fluctuation. The image cancel mixer circuit shown in FIG. 31 is the same as the image cancel mixer circuit shown in FIG. 23, and the same portions are denoted by the same reference numerals.

In the image cancel mixer circuit of FIG. 31, the control voltage input to the changeover switch control circuit 16 is not the output voltage from the temperature detection circuit 17 but the detection voltage obtained from the power supply voltage detection circuit 18. is there. The power supply voltage detection circuit 18 detects the power supply voltage supplied to the mixer circuit, and controls the changeover switch control circuit 16 according to the detected voltage. Then, in response to the detected voltage, are selectively turning on and off the switch SW ₁ to SW _n. By turning on / off these switches, the delay circuits D _{1 to} D _n inserted between the first phase shifter 34 and the third mixer 33 are selected to correct the phase shift due to the power supply voltage fluctuation. it can.

In FIG. 31, a plurality of delay circuits D
₁ has been inserted to D _n between the first phase shifter 34 and the third mixer 33, may be inserted between the second mixer 32 and the third mixer 33. The specific examples described so far show that the image cancel mixer circuit corrects the phase shift due to the power supply voltage fluctuation based on the detected voltage that detects the power supply voltage supplied to the mixer circuit.

Next, in the case where the image signal cannot be removed because the gain is shifted due to the power supply voltage fluctuation in the image cancel mixer circuit, the gain is determined based on the detected voltage obtained by detecting the power supply voltage supplied to the mixer circuit. A specific example of correcting the deviation will be described. FIG. 32 shows the FM
Although the image cancel mixer circuit in the receiver is shown, the basic circuit configuration of this image cancel mixer circuit is the same as that of the image cancel mixer circuit shown in FIG. 24, and the same parts are denoted by the same reference numerals.

A gain control circuit G ₁ is provided in the first mixer 31, and a variable resistor R _v such as an FET is connected to control the gain of the gain control circuit G ₁ . Then, the detection voltage obtained from the power supply voltage detection circuit 18 is supplied to the variable resistor _Rv , the resistance value is changed, and the gain control circuit G
To control the _1. Therefore, the 2 input to the third mixer 33
The gain deviation due to the power supply voltage fluctuation of the two signals is corrected.

Although FIG. 32 shows the case where the first mixer 31 is provided with a gain control circuit, the second mixer 32 may be provided with a gain control circuit. Good. Further, in FIG. 32, the case with a gain control circuit G ₁ inside the mixer, 33, the second
Gain control circuit G ₂ between mixer 32 and third mixer 33
Is shown. The basic circuit configuration of the image cancel mixer circuit is the same as that of FIG. 25, and the same parts are denoted by the same reference numerals.

[0098] The gain control circuit G ₂ is also a variable resistor R _v is connected, a variable resistor R _v supplies a detection voltage obtained from the supply voltage detection circuit 18, the change of the resistance value the gain control circuit G ₂ Control. Therefore, the gain deviation due to the power supply voltage fluctuation of the two signals input to the third mixer 33 is corrected. As described above, specific examples of various means for correcting a phase shift or a gain shift due to a power supply voltage change in the image cancel mixer circuit based on a detection voltage that detects a change in the power supply voltage supplied to the mixer circuit are described. Although the control to remove the image signal has been described, the image signal may be removed by combining a means for correcting a phase shift or a means for correcting a gain shift according to the cause of generation of the image signal.

When the APF is inserted between the mixers to correct the phase shift as shown in FIG.
In PF, replacing the feedback resistance R _a of the AMP to the variable resistor R _v, the detection voltage detected ambient temperature may be supplied. By controlling the gain of the APF, not only can a gain shift be corrected, but also a phase shift can be corrected.

[0100]

As described above, according to the present invention, in the image cancellation mixer circuit, the phase shift and the gain shift due to the variation of each circuit characteristic corresponding to the reception frequency are achieved.
For the phase shift and gain shift due to temperature fluctuation, and the phase shift and gain shift due to power supply voltage change, each phase shift and gain shift can be corrected by each detection voltage, so the image signal is reliably removed. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing a block circuit configuration of a conventional FM stereo receiver.

FIG. 2 is a diagram illustrating image disturbance.

FIG. 3 is a diagram illustrating a conventional example of an image cancel mixer circuit.

FIG. 4 is a diagram showing a block circuit configuration of an FM stereo receiver including an image cancellation mixer circuit for correcting a phase and a gain shift.

FIG. 5 is a diagram illustrating a basic circuit configuration of an APF.

FIG. 6 is a graph illustrating a phase shift with respect to an FM broadcast reception frequency.

FIG. 7 is a diagram showing a specific example of a phase shifter using an APF.

FIG. 8 is a diagram showing a specific example of a phase shifter using an APF.

FIG. 9 is a diagram showing a specific example of a phase shifter using an APF.

FIG. 10 is a diagram illustrating a specific example of an image cancel mixer circuit that performs phase shift correction using an APF.

FIG. 11 is a diagram illustrating a specific example of an image cancellation mixer circuit that performs phase shift correction using an APF.

FIG. 12 is a diagram showing operation waveforms of a phase shifter using a flip-flop.

FIG. 13 is a diagram illustrating a specific example of an image cancel mixer circuit that performs phase shift correction using a delay circuit.

FIG. 14 is a diagram illustrating a specific example of an image cancel mixer circuit that performs phase shift correction using an APF.

FIG. 15 is a diagram illustrating a specific example of an image cancel mixer circuit that performs phase shift correction using a delay circuit.

FIG. 16 is a diagram illustrating a specific example of an image cancel mixer circuit that performs gain shift correction using a gain control circuit.

FIG. 17 is a diagram illustrating a specific example of an image cancel mixer circuit that performs gain shift correction using a gain control circuit.

FIG. 18 is a diagram illustrating a block circuit configuration of an FM stereo receiver including an image cancellation mixer circuit that corrects a phase shift due to an influence of an ambient temperature.

FIG. 19 is a diagram illustrating a specific example of an image cancellation mixer circuit that corrects a phase shift due to temperature using an APF.

FIG. 20 is a diagram illustrating a specific example of an image cancellation mixer circuit that corrects a phase shift due to temperature using an APF.

FIG. 21 is a diagram illustrating a specific example of an image cancellation mixer circuit that corrects a phase shift due to temperature using a delay circuit.

FIG. 22 is a diagram illustrating a specific example of an image cancellation mixer circuit that corrects a phase shift due to temperature using an APF.

FIG. 23 is a diagram illustrating a specific example of an image cancel mixer circuit that corrects a phase shift due to temperature using a delay circuit.

FIG. 24 is a diagram illustrating a specific example of an image cancellation mixer circuit that corrects a gain shift due to temperature using a gain control circuit.

FIG. 25 is a diagram illustrating a specific example of an image cancellation mixer circuit that corrects a gain shift due to temperature using a gain control circuit.

FIG. 26 is a diagram illustrating a block circuit configuration of an FM stereo receiver including an image cancellation mixer circuit that corrects a phase shift due to the influence of power supply voltage fluctuation.

FIG. 27 is a diagram illustrating a specific example of an image cancellation mixer circuit that corrects a phase shift due to a power supply voltage variation using an APF.

FIG. 28 is a diagram illustrating a specific example of an image cancel mixer circuit that corrects a phase shift due to a power supply voltage variation using an APF.

FIG. 29 is a diagram illustrating a specific example of an image cancel mixer circuit that corrects a phase shift due to power supply voltage fluctuation using a delay circuit.

FIG. 30 is a diagram illustrating a specific example of an image cancel mixer circuit that corrects a phase shift due to a power supply voltage variation using an APF.

FIG. 31 is a diagram illustrating a specific example of an image cancel mixer circuit that corrects a phase shift due to power supply voltage fluctuation using a delay circuit.

FIG. 32 is a diagram illustrating a specific example of an image cancel mixer circuit that corrects a gain deviation due to a power supply voltage fluctuation using a gain control circuit.

FIG. 33 is a diagram illustrating a specific example of an image cancellation mixer circuit that corrects a gain deviation due to a power supply voltage fluctuation using a gain control circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Antenna 2 ... High frequency amplifier 3, 3a-3c ... Image cancellation mixer circuit 4 ... Intermediate frequency amplifier 14 ... Tuning circuit 15 ... Local oscillation circuit 16 ... Changeover switch control circuit 17 ... Temperature detection circuit 18 ... Power supply voltage detection circuit 31 ... the first mixer 32 ... second mixer 33 ... third mixer 34 ... first phase shifter 35 ... second phase shifter 36 ... low-pass filter APF1～APF4 ... all-pass filter _{D 1 ~D n, D 11 ~D} 2n ... Delay circuits G ₁ , G ₂ ... gain control circuits

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 5J098 AA05 AA11 AB03 AC13 AC15 AC17 AC18 AD05 AD06 AD07 DA01 5K020 CC03 DD02 DD21 DD23 FF00 HH00 HH02 KK04 NN00 NN01 5K052 AA01 BB04 CC04 DD05 GG00 GG04 GG26 AGG11 CC11 CC45 CC52 CD01 JJ09 JJ11

Claims (19)

[Claims] 1. A radio receiver having an image cancel mixer circuit for mixing a received high-frequency signal and a local oscillation signal to convert the mixed signal into an intermediate frequency signal, wherein the image cancel mixer circuit includes the received high-frequency signal and the local oscillation signal. A first mixer that mixes a signal with the signal, a second mixer that mixes the signal shifted by 90 degrees from the local oscillation signal with the received high-frequency signal, a signal that is shifted by 90 degrees from the first mixer, A radio receiver including a third mixer that mixes a signal from a second mixer and a phase adjustment unit that corrects a phase shift in the image cancellation mixer circuit. 2. The radio receiver according to claim 1, wherein said phase adjusting means can change the phase based on a tuning voltage output from a tuning circuit. 3. The radio receiver according to claim 1, wherein said phase adjusting means can change a phase based on a detection voltage output from a temperature detection circuit for detecting a peripheral temperature of said image cancellation mixer circuit. 4. The radio receiver according to claim 1, wherein said phase adjusting means can change the phase based on a detection voltage from a power supply voltage detection circuit for detecting a change in the power supply voltage. 5. The radio receiver according to claim 2, wherein the phase adjustment unit is an all-pass filter including a variable impedance. 6. The radio receiver according to claim 5, wherein the variable impedance is a variable capacitance. 7. The radio receiver according to claim 5, wherein said variable impedance is a variable resistor. 8. The radio receiver according to claim 2, wherein the phase adjustment unit can change the phase by switching a plurality of delay circuits having different delay amounts. 9. The image cancellation mixer circuit according to claim 1,
An all-pass filter having a fixed phase output and an all-pass filter having a variable phase output generate a phase-shifted signal of the local oscillation signal and include a phase shift circuit for supplying the signal to the first mixer and the second mixer. The radio receiver according to any one of claims 2 to 4, further comprising the phase adjustment unit. 10. The image cancellation mixer circuit includes: an all-pass filter that can vary a duty ratio of the local oscillation signal; and two flip-flops that respectively divide the output signal of the all-pass filter by １ ／. The radio receiver according to any one of claims 2 to 4, further comprising the phase adjustment unit including a phase shift circuit that shifts a phase by 90 degrees between output signals of two flip-flops. 11. The image cancellation mixer circuit includes: a phase shift circuit that can select the plurality of first delay circuits having different delay amounts from each other and vary the phase of the local oscillation signal supplied to the second mixer. A phase shift circuit that can select a plurality of second delay circuits having different delay amounts from each other to supply a signal from the first mixer to the third mixer and change the phase, and A radio receiver according to any one of claims 2 to 4. 12. The radio receiver according to claim 2, wherein said phase adjusting means is inserted into an input signal of said third mixer. 13. A radio receiver having an image cancel mixer circuit for mixing a received high-frequency signal and a local oscillation signal to convert the mixed signal into an intermediate frequency signal, wherein the image cancel mixer circuit comprises the received high-frequency signal and the local oscillation signal. A first mixer that mixes a signal with the signal, a second mixer that mixes the signal shifted by 90 degrees from the local oscillation signal with the received high-frequency signal, a signal that is shifted by 90 degrees from the first mixer, A radio receiver including a third mixer that mixes a signal from a second mixer and a gain control unit that corrects a gain shift in the image cancellation mixer circuit. 14. The radio receiver according to claim 13, wherein said gain control means can change a gain based on a tuning voltage output from a tuning circuit. 15. The radio receiver according to claim 13, wherein said gain control means can change a gain based on a detection voltage output from a temperature detection circuit for detecting an ambient temperature of said image cancellation mixer circuit. 16. The radio receiver according to claim 13, wherein said gain control means can change a gain based on a detection voltage from a power supply voltage detection circuit for detecting a change in a power supply voltage. 17. The radio receiver according to claim 14, wherein said gain control means has a variable impedance, and adjusts a gain by controlling the impedance value. 18. The radio receiver according to claim 14, wherein said gain control means is provided in said first mixer or said second mixer. 19. The radio receiver according to claim 14, wherein said gain control means is inserted into an input signal of said third mixer.