JP2002094329A - Microwave band doubly balanced mixer circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microwave band doubly balanced mixer circuit used for a microwave band, that prevents operation from becoming unstable due to the oscillation of the circuit itself. SOLUTION: In the microwave band doubly balanced mixer circuit of this invention, bases of each pair of transistors(TR) are placed closely for the connection in the shortest distance, common-mode local oscillation signals are applied to the bases of the pair of TRs, high-frequency amplifier signals with different phases are applied to the emitters of the pair TRs to mix the local oscillation signals and the high-frequency amplifier signals and to extract an intermediate frequency signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave band double-balanced mixer circuit used in a portable telephone or the like using a high frequency signal in a microwave band.

[0002]

2. Description of the Related Art In a radio communication device such as a portable telephone using a microwave band high-frequency signal, a microwave band high-frequency signal received by an antenna is first amplified by a high-frequency amplifier circuit and then frequency-converted by a mixer circuit. Further, demodulation and the like are performed.

FIG. 2 is an example of a block diagram of a high-frequency portion of a portable telephone using a conventional double-balanced mixer circuit. 1 is a receiving unit that processes a received signal received via an antenna or a cable or the like, and 2 is a transmitting unit that processes a transmission signal transmitted via an antenna or a cable or the like.

The receiving section 1 is a high-frequency amplifier circuit 5 for amplifying a high-frequency signal in a microwave band received by an antenna or the like.
And a local oscillator 7 composed of a voltage-controlled oscillator whose oscillation frequency is controlled by the PLL 6, and a local oscillation signal applied from the local oscillator 7 via the buffer amplifier 6 to a high-frequency signal from the high-frequency amplifier circuit 5. Mixer circuit 9
And an intermediate frequency amplifying circuit 10 for amplifying the intermediate frequency signal converted by the mixer circuit 9.

[0005] A transmitting section 2 includes an intermediate frequency amplifying circuit 1 for amplifying an intermediate frequency signal obtained by converting a transmission signal to be transmitted.
7, a mixer circuit 19 for mixing the intermediate frequency signal from the intermediate frequency amplifier circuit 17 with a local oscillation signal applied from the local oscillator 7 via a buffer amplifier 18, and a high frequency signal in the microwave band from the mixer circuit 19. Amplify,
And a high-frequency amplifier circuit 20 for supplying the antenna.

In the receiving state, the high-frequency signal applied to the high-frequency amplifier circuit 5 via the antenna is amplified by the high-frequency amplifier circuit 5 and further added to the mixer circuit 9 to be mixed with the local oscillation signal from the local oscillator. An intermediate frequency signal is extracted from the circuit 9 and amplified by the intermediate frequency amplifier circuit 10.

The mixer circuit 9 includes a transistor 21 and a transistor 22 whose emitters are arranged oppositely and connected, similarly a transistor 23 and a transistor 24 whose emitters are arranged oppositely and connected, and the transistor 21 and the transistor A transistor 25 has a collector connected to the emitter connected to the transistor 22, and a transistor 26 has a collector connected to the emitter connected to the transistors 23 and 24.

The transistor 21 and the transistor 24
Are connected to each other, and the transistor 22
And the base of the transistor 23 are connected. Further, the collectors of the transistors 21 and 23 are connected and the power supply voltage Vcc is applied via a resistor 27. Similarly, the collectors of the transistors 22 and 24 are connected and the power supply voltage Vcc is connected via a resistor 28. Is added.

The transistor 25 and the transistor 26
Are connected via a resistor 31 and
They are grounded via resistors 29 and 30, respectively.

The output stage of the high-frequency amplifier 5 is constituted by a differential amplifier, and the amplified high-frequency amplified signal Rf + and the high-frequency amplified signal Rf- which is 180 degrees out of phase with the high-frequency amplified signal Rf + are output. The high frequency amplified signal R
f + is applied to the base of transistor 25 and high frequency signal Rf- is applied to the base of transistor 26.

The buffer amplifier 8 is constituted by a differential amplifier, buffers the local oscillation signal from the local oscillator 7, and outputs the local oscillation signal Lo + and the local oscillation signal Lo +.
A local oscillation signal Lo- having a phase difference of 80 degrees is output, and the local oscillation signal Lo + is
4 and the local oscillation signal Lo- is applied to the bases of the transistors 22 and 23.

A local oscillation signal Lo + is applied to the base of the transistor 21, and a high-frequency amplified signal Rf + is applied to the emitter.
Is added, and an intermediate frequency signal is extracted from the collector. A local transmission signal Lo- is applied to the base of the transistor 23, and the high-frequency amplified signal R-
f- is applied and an intermediate frequency signal IF + is taken from the collector.

Similarly, the local oscillation signal Lo- is applied to the base of the transistor 22 and the high-frequency amplification signal Rf + is applied to the emitter, so that the signal is mixed and the intermediate frequency signal is extracted from the collector. The local oscillation signal Lo + is applied to the base of the transistor 24, the high-frequency amplified signal Rf- is applied to the emitter, and the intermediate frequency signal IF- is applied from the collector.
Is taken out.

The extracted intermediate frequency signal IF + and intermediate frequency signal IF- are applied to a differential amplifier preceding the intermediate frequency amplifier 10.

[0015]

When the double-balanced mixer circuit is used in the microwave band, if the wiring length of the base of the transistor to be connected becomes long, a signal phase difference occurs between the transistors and abnormal oscillation occurs. In some cases, the operation itself became unstable.

[0016]

A double-balanced mixer circuit according to the present invention is provided so that the bases of a first transistor and a second transistor and the bases of a third transistor and a fourth transistor are connected to each other at the shortest distance, and a first local mixer is provided. An oscillating signal is applied to the bases of the first and second transistors, a second local oscillating signal is applied to the bases of the third and fourth transistors, and the emitters of the first and third transistors are connected. Adding a first high-frequency amplified signal from a transistor, connecting the emitters of a second transistor and a fourth transistor, adding a second high-frequency amplified signal from the sixth transistor, connecting the collectors of the first and fourth transistors, Take out the first intermediate frequency signal and connect the collectors of the second and third transistors Forming a structure for taking out the second intermediate frequency signal.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A microwave band double balanced mixer circuit according to the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a microwave-band double-balanced mixer circuit according to the present invention.

Reference numeral 1 denotes a reception unit for processing a reception signal received via an antenna or a cable or the like, and reference numeral 2 denotes a transmission unit for processing a transmission signal transmitted via an antenna or a cable or the like.

The receiving section 1 is a high-frequency amplifier circuit 5 for amplifying a high-frequency signal in a microwave band received by an antenna or the like.
And a local oscillator 7 composed of a voltage-controlled oscillator whose oscillation frequency is controlled by the PLL 6, and a local oscillation signal applied from the local oscillator 7 via the buffer amplifier 6 to a high-frequency signal from the high-frequency amplifier circuit 5. Mixer circuit 9
And an intermediate frequency amplifying circuit 10 for amplifying the intermediate frequency signal converted by the mixer circuit 9.

A transmitting section 2 is an intermediate frequency amplifier circuit 1 for amplifying an intermediate frequency signal obtained by converting a transmission signal to be transmitted.
7, a mixer circuit 19 for mixing the intermediate frequency signal from the intermediate frequency amplifier circuit 17 with a local oscillation signal applied from the local oscillator 7 via a buffer amplifier 18, and a high frequency signal in the microwave band from the mixer circuit 19. And a high-frequency amplifier circuit 20 for amplifying the same and supplying the amplified signal to the antenna.

In the receiving state, a high-frequency signal applied to the high-frequency amplifier circuit 5 via an antenna or a cable is amplified by the high-frequency amplifier circuit 5 and further added to the mixer circuit 9 where the signal is mixed. In the mixer circuit 9, the high-frequency signal and the local oscillation signal from the local oscillator 7 are mixed, and an intermediate frequency signal is extracted and amplified by the intermediate frequency amplifier circuit 10.

By the way, the mixer circuit 9 is close to the first transistor 35 and the second transistor 36 provided close to each other so that the base is connected to the shortest distance, similarly to the mixer circuit 9 so that the base is connected to the shortest distance. The third transistor 37 and the fourth transistor 38 provided, the fifth transistor 39 to which the first high-frequency amplification signal Rf + amplified by the high-frequency amplifier 5 is added to the base, and the 180-degree angle amplified by the high-frequency amplifier 5 to the base. A sixth transistor 40 to which a second high-frequency amplified signal Rf- having a different phase is added.

The characteristic impedance and the electrical length of the wiring connecting the bases of the first transistor 35 and the second transistor 36 and the base of the third transistor 37 and the fourth transistor 38 are made the same.

The emitters of the first transistor 35 and the third transistor 37 are connected, and the fifth transistor 3
9 is added to the high-frequency amplified signal Rf +
The emitters of the transistor 36 and the fourth transistor 38 are connected, and the high-frequency amplified signal Rf- from the sixth transistor 40 is applied.

Further, the collectors of the first transistor 35 and the fourth transistor 38 are connected and the power supply voltage Vcc is applied to the resistor 41. Similarly, the collectors of the second transistor 36 and the third transistor 37 are connected and the resistor 42 is connected to the power source. Voltage Vcc is applied.

As described above, the local transmission signal Lo + is applied to the base of the first transistor 35, and the high-frequency amplified signal Rf + is added to the emitter, and the mixer is mixed. The local transmission signal Lo- is added to the base of the fourth transistor 38, and the high-frequency amplified signal Rf- is added to the emitter, and the mixer is mixed.

Similarly, the local transmission signal Lo + is added to the base of the second transistor 36, the high-frequency amplified signal Rf- is added to the emitter and mixed, and the local transmission signal Lo- is added to the base of the fourth transistor 38. Is mixed.

The local oscillator 7 receives the control signal PL
L6 is controlled, and the local oscillator 7 oscillates a local oscillation signal having a frequency just different from the high-frequency signal by the intermediate frequency. IF + is taken out, and the intermediate frequency signal IF + is taken out from the emitters of the second transistor 36 and the third transistor 37.

The extracted intermediate frequency signal IF + and intermediate frequency signal IF− are applied to a differential amplifier preceding the intermediate frequency amplifier 10.

[0031]

According to the double-balanced mixer circuit of the present invention, one base of the first transistor and the second transistor and one base of the third transistor and the fourth transistor are provided close to each other so as to be connected at the shortest distance. Can minimize the stray capacitance or inductance of the wiring connecting the circuit, and can stabilize the circuit operation up to high frequencies.

Further, by making the characteristic impedance and the electrical length of the wiring connecting the bases of the respective transistors the same, it is possible to prevent the occurrence of the phase difference of the signal between the respective transistors and the occurrence of the abnormal oscillation.

[Brief description of the drawings]

FIG. 1 is a block diagram of a microwave band double balanced mixer circuit of the present invention.

FIG. 2 is a block diagram of a conventional microwave band double balanced mixer circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Receiving part 2 Transmitting part 5 High frequency amplifier circuit 7 Local oscillation circuit 9 Mixer circuit 10 Intermediate frequency amplifier circuit 35 1st transistor 36 2nd transistor 37 3rd transistor 38 4th transistor 39 5th transistor 40 6th transistor

Claims (2)

[Claims] 1. A first transistor 35 and a second transistor 36 provided close to each other so that a base is connected to the shortest distance, and a third transistor 37 provided close to a base so as to be connected to the shortest distance. A fourth transistor 38, a fifth transistor 39 to which a first high frequency amplified signal Rf + amplified by the high frequency amplifier 5 is added to a base, and a first high frequency amplified signal Rf + amplified by the high frequency amplifier 5 to the base and 180. A sixth local oscillator 40 to which a second high-frequency amplified signal Rf- having a different phase is added. A first local oscillation signal from the local oscillator 7 is applied to the bases of the first transistor 35 and the second transistor 36. A second local oscillation signal from a local oscillator 180 degrees out of phase with the first local oscillation signal is supplied to the third transistor 37.
In addition to the base of the fourth transistor 38 and the emitters of the first transistor 35 and the third transistor 37, the first high-frequency amplified signal Rf + from the fifth transistor 39 is added, and the second transistor 36 and the fourth transistor 38 , The second high-frequency amplified signal Rf- from the sixth transistor 40 is added, the collectors of the first transistor 35 and the fourth transistor 38 are connected, the first intermediate frequency signal IF + is taken out, and the second The transistor 36 and the collector of the third transistor 37 are connected, and the second intermediate frequency signal is 180 degrees out of phase with the second intermediate frequency signal.
The intermediate frequency signal IF- is taken out and the intermediate frequency amplifier 10
A microwave band double-balanced mixer circuit characterized in that: 2. A first transistor 35 and a second transistor 36, and a third transistor 37 and a fourth transistor 38.
2. The microwave-balanced double-balanced mixer circuit according to claim 1, wherein the characteristic impedance and the electrical length of the wiring connecting each of the bases are the same.