JPH0983254A - High frequency mixer circuit and reception converter using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the high frequency mixer circuit in which intermodulation distortion is reduced by a mixer circuit by providing a coil circuit between balun balanced terminals even when an individual difference arises in manufactured baluns and to obtain the reception converter using the high frequency mixer circuit. SOLUTION: In a double balanced mixer circuit consisting of a 1st balun 7, a 2nd balun 8 and a diode bridge 9, coils 1, 2 are provided between the balun 7 and the bridge 9. The coil 1 is connected between balanced terminals of the 1st balun 7 and the coil 2 is connected between a midpoint 30 of the coil 1 and ground. Thus, a phase difference between the balanced terminals of the 1st balun 7 approaches 180 deg. without limit so as to suppress a deviation in the phase difference between the balanced terminals due to manufacturing thereby reducing considerably intermodulation distortion in the high frequency mixer circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency mixer circuit used in a wide band receiver such as a tuner and a converter, and a receiving converter using the same.

[0002]

2. Description of the Related Art Conventionally, a high frequency mixer circuit of this type is shown in FIG.
It had the structure shown in. In FIG. 9, 7 and 8 are first and second baluns, and a diode bridge 9 composed of four diodes is connected between the balanced terminals of the first and second baluns. Grounded to the unbalanced terminal and the common terminal of the balun 8, and the unbalanced terminal of the first balun 7 as the local oscillation input terminal 12, the common terminal of the first balun 7 as the signal input terminal 11, and the second balun. 8
The unbalanced terminal of 1 was used as the intermediate frequency output terminal 13.

[0003]

However, in the case of the above configuration, the manufactured balun has individual differences, and the phase difference between the balanced terminals of the balun is not ideally 180 °, so that the intermodulation distortion is generated. There was a problem that it could not be reduced by the mixer circuit and interfered with the reception frequency.

An object of the present invention is to solve the above problems and to provide a high frequency mixer circuit capable of reducing intermodulation distortion in the mixer circuit even if individual differences occur in manufactured baluns, and a receiving converter using the same. To do.

[0005]

In order to solve this problem, a high frequency mixer circuit according to the present invention comprises a diode bridge between a first balun and a second balun,
The balun has a signal input terminal and a local oscillation input terminal,
An intermediate frequency output terminal is provided on the second balun, and
Of the first coil connected between the balanced terminals of the balun, or is grounded via the second coil from the middle point or a point deviated from the middle point.

In the receiving converter according to the present invention, a diode bridge is provided between the first balun and the second balun, the first balun is provided with a signal input terminal and a local oscillation input terminal, and the second balun is provided. And a high frequency mixer circuit in which an intermediate frequency output terminal is provided on the balun, and a midpoint of the first coil connected between the balanced terminals of the first balun or a point deviated from the midpoint is grounded via a second coil. A PLL oscillation circuit connected to a local oscillation input terminal of the high-frequency mixer circuit, an RF amplification circuit connected to a signal input terminal of the high-frequency mixer circuit, and an intermediate frequency connected to an intermediate-frequency output terminal of the high-frequency mixer circuit And an amplifier circuit.

[0007]

With the above structure, even if individual differences occur in the manufactured baluns, the phase difference between the balanced terminals of the balun is reduced to 18%.
It becomes possible to set the angle to 0 °, the intermodulation distortion generated in the high frequency mixer circuit can be reduced, and the problem that the reception frequency is disturbed can be solved.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an electric circuit diagram showing a high frequency mixer circuit according to an embodiment of the present invention. The first balun 7 and the second balun 8 are manufactured by winding a bifilar wire around a spectacle-shaped magnetic core, and the first balun 7 and the second balun 8 and a diode bridge 9 composed of four diodes are used. It constitutes a double balanced mixer circuit. The unbalanced terminal of the first balun 7 is the local oscillation input terminal 12, the common terminal of the first balun 7 is the signal input terminal 11, the unbalanced terminal of the second balun 8 is the intermediate frequency output terminal 13, and the high frequency It improves the frequency conversion efficiency of the mixer circuit. In addition,
The signal input terminal 11 and the local oscillation input terminal 12 may be used in reverse. As shown in FIG. 1, in this example, the first coil 1 and the second coil 2 were used. The first coil 1 is connected between the balanced terminals of the first balun 7, and the second coil 2 is connected between the midpoint 30 of the first coil 1 and ground. By connecting in this way,
The phase difference between the balanced terminals of the first balun 7 approaches the ideal 180 ° without limit. As a result, the first
The balun 7 can suppress the deviation of the phase difference between the balanced terminals that occurs during manufacturing, and can significantly reduce the intermodulation distortion in the high frequency mixer circuit.

FIG. 2 is a top view showing a mounting state of a high frequency mixer circuit according to another embodiment of the present invention. The first coil 1 uses a jumper wire, and the second coil 2 uses a lead inductor. In this state, the lead inductor that is the second coil 2 is grounded by the partition plate 20 that is arranged parallel to the long side direction of the first balun 7. With this configuration, the deviation of the phase difference between the balanced terminals of the first balun 7 is further suppressed. As a result, the intermodulation distortion generated in the high frequency mixer circuit is further reduced. Further, as shown in FIG. 2, the jumper wire which is the first coil 1 is formed in an arc shape and has a mountain-like configuration in the vertical direction. Further, the midpoint 30 of the first coil 1 is spatially connected to one end of the second coil 2. At this time, the first coil 1 is tilted in a direction away from the first balun 7 to prevent deterioration of the frequency characteristic that occurs when the first coil 1 and the first balun 7 are magnetically coupled. ing.

FIG. 3 is a top view showing a mounting state of a high frequency mixer circuit according to another embodiment of the present invention. The second coil 2 is connected between the connection point 30a, which is the first coil 1 and which is displaced from the midpoint of the jumper wire, and the ground point formed by the partition plate 20. By thus shifting the connection point 30a from the midpoint 30, the intermodulation distortion generated in the high frequency mixer circuit is optimally reduced. The second coil 2 is arranged near the center of the upper part of the magnetic core of the first balun 7 so as to keep the first balun 7 from being affected by the second coil 2. The relationship between the inductance value (L1) of the first coil 1 and the inductance value (L2) of the second coil 2 is always L1 <L2.

FIG. 4 is a top view showing a mounting state of a high frequency mixer circuit according to another embodiment of the present invention. The first coil 1a is formed of a microstrip line, and the second coil 2a is formed of a chip inductor. At this time, one end of the second coil 2a is grounded to the back surface of the double-sided board through the through hole 70. As shown in FIG. 4, the first coil 1a is patterned in a direction away from the first balun 7, and the second coil 2a is arranged between the first coil 1a and the first balun 7. There is. With this arrangement, the deviation of the phase difference between the balanced terminals of the first balun 7 is suppressed. The microstrip line that is the first coil 1a is not patterned in a straight line, but is formed at several angles, so that the inductance value can be adjusted by cutting a part of this microstrip line. I have to.

FIG. 5 is an electric circuit diagram of a high frequency mixer circuit according to another embodiment of the present invention. The parallel resonant circuit 40 is connected between the balanced terminals of the second balun 8 so that the intermediate frequency whose frequency is converted by the high frequency mixer circuit is tuned. With this configuration, the frequency conversion efficiency is increased and the output impedance of the intermediate frequency output terminal 13 is stabilized. This parallel resonance circuit 40
Is composed of a chip inductor and a chip capacitor.

FIG. 6 is a top view showing a mounted state of a high frequency mixer circuit according to another embodiment of the present invention. The coil forming the parallel resonance circuit 40 is a microstrip line 40.
a and the capacitor is arranged on the same surface as the chip capacitor 40b. The microstrip line 40a does not connect the parallel terminals of the second balun 8 in a straight line, but forms a pattern with an angle in the direction away from the second balun 8. By arranging in this way, the second balun 8 and the microstrip line 40a are
Try not to combine. Further, the first balun 7 and the second balun 8 are arranged such that the long side directions thereof are parallel to each other, and the volume (S1) of the first balun 7 and the volume (S2) of the second balun 8 are The relationship is always S1> S2. This improves the conversion efficiency when the low frequency is converted into the high frequency by the high frequency mixer circuit.

In this embodiment, in any case, the first
The balun 7 and the second balun 8 are mounted on the front surface of the double-sided board, and the diode bridge 9 composed of four diodes is mounted on the back surface of the double-sided board.

FIG. 7 is a block diagram of a receiving converter using a high frequency mixer circuit according to another embodiment of the present invention.
The RF amplification circuit 51 is configured by connecting a variable attenuator 62 to the output of the first high frequency amplifier 61 and connecting a second high frequency amplifier 63 to the output of the variable attenuator 62. PL
The output of the L oscillator circuit 52 is connected to the local oscillation input terminal of the high frequency mixer circuit 54, and the output of the RF amplifier circuit 51 is connected to the signal input terminal of the high frequency mixer circuit 54. The intermediate frequency amplifier circuit 53 connects the first intermediate frequency amplifier 65 to the output of the first filter 64, and connects the second filter 66 to the output of the first intermediate frequency amplifier 65.
The output of the second filter 66 is fed to the second intermediate frequency amplifier 67.
The output of the second intermediate frequency amplifier 67 is connected to the third intermediate frequency amplifier 68 and the detection circuit 69, and the output of the detection circuit 69 is connected to the variable attenuator 62. The detection circuit 69 is provided to suppress the output level deviation of the reception converter and stabilizes the frequency characteristic. Further, the first intermediate frequency amplifier 65 is provided between the first filter 64 and the second filter 66, and suppresses the in-band deviation of the intermediate frequency. In order to secure the attenuation characteristics of the adjacent channels, the first filter 64 and the second filter 66 are miniaturized as a dielectric filter having a three-pole structure and at a low price. The input of the detection circuit 69 is connected between the output of the second intermediate frequency amplifier 67 and the third intermediate frequency amplifier 68. By connecting in this way, the signal level input to the detection circuit 69 becomes stable, and the characteristics against output fluctuations from the outside are improved.

FIG. 8 is a top view showing the arrangement of a receiving converter using a high frequency mixer circuit according to another embodiment of the present invention. As shown in FIG. 8, the PLL oscillation circuit 52 is arranged so as to be surrounded by the RF amplification circuit 51, the high frequency mixer circuit 54, and the intermediate frequency amplification circuit 53. Such an arrangement prevents the output of the PLL oscillation circuit 52 and its harmonics from being radiated to the outside of the receiving converter.

[0017]

As described above, according to the present invention, the diode bridge is provided between the first balun and the second balun, and the first balun is provided with the signal input terminal and the local oscillation input terminal. The second balun is provided with an intermediate frequency output terminal, the first coil is connected between the balanced terminals of the first balun, and the second coil is connected from the midpoint of the first coil or a point deviated from the midpoint. Since it is grounded via the balun, even if individual differences occur in the manufactured balun, the phase difference between the balanced terminals of the balun can be 180 °, and the intermodulation distortion that occurs in the high frequency mixer circuit can be reduced. It is possible to solve the problem of interfering with the reception frequency.

[Brief description of drawings]

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

FIG. 2 is a top view showing a mounted state of a high frequency mixer circuit according to another embodiment of the present invention.

FIG. 3 is a top view showing a mounting state of a high frequency mixer circuit according to still another embodiment of the present invention.

FIG. 4 is a top view showing a mounting state of a high frequency mixer circuit according to still another embodiment of the present invention.

FIG. 5 is an electric circuit diagram of a high frequency mixer circuit according to still another embodiment of the present invention.

FIG. 6 is a top view showing a mounting state of a high frequency mixer circuit according to still another embodiment of the present invention.

FIG. 7 is a block diagram of a receiving converter according to an embodiment of the present invention.

FIG. 8 is a top view showing a circuit arrangement of the reception converter.

FIG. 9 is an electrical circuit diagram of a conventional high frequency mixer circuit.

[Explanation of symbols]

 1 1st coil 2 2nd coil 7 1st balun 8 2nd balun 9 Diode bridge 11 Signal input terminal 12 Signal input terminal 12 Local oscillation input terminal 13 Intermediate frequency output terminal 20 Partition plate 30 Midpoint 40 Parallel resonant circuit 51 RF amplification Circuit 52 PLL oscillation circuit 53 Intermediate frequency amplifier circuit 54 High frequency mixer circuit 61 First high frequency amplifier 62 Variable attenuator 63 Second high frequency amplifier 64 First filter 65 First intermediate frequency amplifier 66 Second filter 67 Second Intermediate frequency amplifier 68 Third intermediate frequency amplifier 69 Detection circuit

Claims (12)

[Claims] 1. A diode bridge is provided between a first balun and a second balun, a signal input terminal and a local oscillation input terminal are provided in the first balun, and an intermediate frequency output terminal is provided in the second balun. And a high-frequency mixer circuit in which the midpoint of the first coil connected between the balanced terminals of the first balun is grounded via the second coil. 2. The high frequency mixer circuit according to claim 1, wherein the first coil is a jumper wire and the second coil is a lead inductor. 3. The high frequency mixer circuit according to claim 1, wherein the first coil is formed in an arc shape in a direction away from the first balun. 4. The first coil in place of the middle point of the first coil
The high-frequency mixer circuit according to claim 1, wherein the high-frequency mixer circuit is grounded via a second coil from a point displaced from the midpoint of the coil. 5. The high frequency mixer circuit according to claim 1, wherein the second coil is arranged above the first balun. 6. The inductance value (L
1) and the inductance value (L2) of the second coil are L
The high frequency mixer circuit according to claim 1, wherein the relationship is such that 1 <L2. 7. The high frequency mixer circuit according to claim 1, wherein the first coil is formed of a microstrip line. 8. The high frequency mixer circuit according to claim 7, wherein the microstrip lines are connected so as not to form a straight line. 9. The high frequency mixer circuit according to claim 1, wherein a parallel resonance circuit is connected between the balanced terminals of the second balun. 10. The high frequency mixer circuit according to claim 1, wherein the volume (S1) of the first balun and the volume (S2) of the second balun have a relationship such that S1> S2. 11. The high frequency mixer circuit according to claim 9, wherein the coils forming the parallel resonant circuit are formed by microstrip lines. 12. A diode bridge is provided between the first balun and the second balun, a signal input terminal and a local oscillation input terminal are provided on the first balun, and an intermediate frequency output terminal is provided on the second balun. And a high-frequency mixer circuit grounded via a second coil from a midpoint of the first coil connected between the balanced terminals of the first balun or a point deviated from the midpoint, and a local portion of the high-frequency mixer circuit. A PLL oscillation circuit connected to an oscillation input terminal, an RF amplification circuit connected to a signal input terminal of the high frequency mixer circuit, and an intermediate frequency amplification circuit connected to an intermediate frequency output terminal of the high frequency mixer circuit are provided. Receiver converter.