CN220368697U - Mixer circuit capable of inhibiting 2IF - Google Patents

Abstract

The utility model relates to a mixer circuit capable of inhibiting 2IF, which comprises a 90-degree bridge, wherein an input end IN of the 90-degree bridge is connected with a microwave input signal IF, a first output end of the 90-degree bridge outputs an intermediate frequency signal with a 0-degree phase to an input end of a first attenuator, a second output end of the 90-degree bridge outputs an intermediate frequency signal with a 90-degree phase to an input end of a second attenuator, an output end of the first attenuator outputs a first intermediate frequency signal IF1 to a first mixer, an output end of the second attenuator outputs a second intermediate frequency signal IF2 to a second mixer, the first mixer outputs a first radio frequency signal RF1 to a first input end of a combiner, the second mixer outputs a second radio frequency signal RF2 to a second input end of the combiner, and the output end of the combiner outputs a final microwave radio frequency signal RF out to a band-pass filter. The utility model can realize the function of inhibiting 2IF, and has simple circuit and easy realization; the final microwave radio frequency signal RF out is output through the band-pass filter, and the microwave signal 2IF can be further suppressed.

Description

Mixer circuit capable of inhibiting 2IF

Technical Field

The utility model relates to the technical field of mixer circuits, in particular to a mixer circuit capable of inhibiting 2 IF.

Background

In radar microwave systems, a mixer circuit is a common basic circuit used for frequency spectrum shifting of radio frequency signals. As mixer circuits are applied in more fields and scenarios, the output spurious suppression requirements for mixer circuits are also becoming more and more diverse. In a radar microwave system, on the premise of designating intermediate frequency and local oscillation frequency, a mixing circuit is required to mix frequencies, and then a combination spurious (for example, 2IF+LO) which is different from a frequency point of a required signal by less than 50MHz is required to have higher inhibition capability. The source of the combination spurious is analyzed to show that the combination spurious is composed of 2IF leakage and Local Oscillator (LO) signal leakage after mixing, so that the 2IF signal and the local oscillator signal are restrained, and the restraint of the combination spurious 2IF+LO can be achieved.

The mixing modes commonly used at present are as follows: firstly, by utilizing the existing mixer device, a microwave intermediate frequency signal is directly input into an intermediate frequency port of a single-stage mixer, a microwave local oscillation signal is directly input into a local oscillation port of the single-stage mixer, and frequency spectrum shifting is realized; secondly, a PLL phase-locked loop is utilized to respectively input a microwave input signal and a reference signal into the PLL phase-locked loop, a frequency divider is arranged in the PLL phase-locked loop, and the frequency spectrum of the microwave input signal is shifted through a feedback mechanism of the PLL phase-locked loop and frequency division times, and the frequency mixing mode ensures that the frequency accuracy of an output signal is high, but the circuit is complex, the implementation is difficult, and the unlocking condition of the PLL phase-locked loop possibly occurs; thirdly, the DDS direct digital frequency synthesizer is utilized to input microwave input signals and reference signals to the DDS direct digital frequency synthesizer respectively, and the output frequency adjustment of a loop is realized by changing frequency control words of the direct digital frequency synthesizer, so that the frequency spectrum movement of the microwave signals is realized.

Therefore, how to develop a mixer circuit which is easy to realize and can suppress 2IF has become an urgent technical problem to be solved.

Disclosure of Invention

In order to solve the problems that the existing mixer circuit cannot restrain 2IF, is complex in circuit and difficult to realize, the utility model aims to provide a mixer circuit capable of restraining 2IF, which is simple and easy to realize and can restrain 2 IF.

In order to achieve the above purpose, the present utility model adopts the following technical scheme: the mixer circuit capable of suppressing 2IF comprises a 90-degree bridge, wherein an input end IN of the 90-degree bridge is connected with a microwave input signal IF, a first output end of the 90-degree bridge outputs an intermediate frequency signal with 0-degree phase to an input end of a first attenuator, a second output end of the 90-degree bridge outputs an intermediate frequency signal with 90-degree phase to an input end of a second attenuator, an output end of the first attenuator outputs a first intermediate frequency signal IF1 to a first mixer, an output end of the second attenuator outputs a second intermediate frequency signal IF2 to a second mixer, an input end of a second power divider is connected with a local oscillator signal LO, a first output end of the second power divider outputs a first local oscillator signal LO1 to a local oscillator port of the first mixer, a second output end of the second power divider outputs a second local oscillator signal LO2 to a local oscillator port of the second mixer, the first mixer outputs a first radio frequency signal RF1 to a first input end of a combiner, the second mixer outputs a second radio frequency signal RF2 to a second input end of the combiner, and an output end of the combiner outputs a microwave radio frequency signal RF to a final band-pass filter.

The first local oscillation signal LO1 and the second local oscillation signal LO2 are in the same frequency and phase.

According to the technical scheme, the beneficial effects of the utility model are as follows: firstly, the microwave input signal IF is respectively output with an intermediate frequency signal with the phase of 0 DEG and an intermediate frequency signal with the phase of 90 DEG through the 90 DEG bridge, and then is respectively mixed with the first mixer and the second mixer, and the first radio frequency signal RF1 output by the first mixer and the second radio frequency signal RF2 output by the second mixer are combined through the combiner to output the microwave radio frequency signal RF, so that the 2IF inhibition function is realized, and the circuit is simple and easy to realize; and secondly, the microwave radio frequency signal RF output by the combiner is output to a final microwave radio frequency signal RF out through a band-pass filter, so that the microwave signal 2IF can be further suppressed.

Drawings

Fig. 1 is a schematic circuit diagram of the present utility model.

Detailed Description

As shown IN fig. 1, a mixer circuit capable of suppressing 2IF includes a 90 ° bridge 1, an input terminal IN of which is connected to a microwave input signal IF, a first output terminal of the 90 ° bridge 1 outputs an intermediate frequency signal of 0 ° phase to an input terminal of a first attenuator 2, a second output terminal of the 90 ° bridge 1 outputs an intermediate frequency signal of 90 ° phase to an input terminal of a second attenuator 3, an output terminal of the first attenuator 2 outputs the first intermediate frequency signal IF1 to a first mixer 4, an output terminal of the second attenuator 3 outputs a second intermediate frequency signal IF2 to a second mixer 5, an input terminal of a second power divider 6 is connected to a local oscillator signal LO, a first output terminal of the second power divider 6 outputs the first local oscillator signal LO1 to a local oscillator port of the first mixer 4, a second output terminal of the second power divider 6 outputs the second local oscillator signal LO2 to a first input terminal of a combiner 7, the second mixer 5 outputs the second radio frequency signal RF1 to a second input terminal of a combiner 7, and an output terminal of the second mixer 5 outputs the second radio frequency signal RF2 to a band-pass filter 8. The first local oscillation signal LO1 and the second local oscillation signal LO2 are in the same frequency and phase.

According to the utility model, the microwave input IF signal is respectively output with an intermediate frequency signal with 0 degree phase and an intermediate frequency signal with 90 degrees phase through the 90-degree bridge 1, and then is respectively mixed with the first mixer 2 and the second mixer 3, after mixing, the phase difference of the first spurious signal 2IF1 in the first radio frequency signal RF1 and the phase difference of the second spurious signal 2IF2 in the second radio frequency signal RF2 are 180 degrees, after the first radio frequency signal RF1 and the second radio frequency signal RF2 are synthesized into the microwave radio frequency signal RF through the combiner 7, the first spurious signal 2IF1 and the second spurious signal 2IF2 are offset to a certain extent due to the 180-degree phase difference, so that the 2IF inhibition function is realized, and the circuit is simple and easy to realize.

The higher the IP2 index is, the better the first mixer 4 and the second mixer 5 are when selected; during the selection of the combiner 7, care should be taken that the bandwidth of the combiner 7 includes the combined spurious components to be suppressed, namely 2if+lo; the 90-degree bridge 1, the first attenuator 2, the second attenuator 3 and the second power divider 6 are selected according to the required technical index parameters.

In summary, the microwave input signal IF is respectively output by the 90 ° bridge 1 with the intermediate frequency signal of the phase 0 ° and the intermediate frequency signal of the phase 90 ° and then is respectively mixed with the first mixer 2 and the second mixer 3, and the first radio frequency signal RF1 output by the first mixer 2 and the second radio frequency signal RF2 output by the second mixer 3 are combined by the combiner 7 to output the microwave radio frequency signal RF, so that the 2IF suppression function is realized, the circuit is simple and easy to realize; the microwave radio frequency signal RF output by the combiner 7 is output to the final microwave radio frequency signal RF out through the band-pass filter 8, so that the microwave signal 2IF can be further suppressed.

Claims (2)

1. A mixer circuit capable of suppressing 2IF, characterized by: the microwave frequency synthesizer comprises a 90-degree bridge (1), wherein an input end IN of the 90-degree bridge (1) is connected with a microwave input signal IF, a first output end of the 90-degree bridge (1) outputs an intermediate frequency signal with 0-degree phase to an input end of a first attenuator (2), a second output end of the 90-degree bridge (1) outputs an intermediate frequency signal with 90-degree phase to an input end of a second attenuator (3), an output end of the first attenuator (2) outputs a first intermediate frequency signal IF1 to a first mixer (4), an output end of the second attenuator (3) outputs a second intermediate frequency signal IF2 to a second mixer (5), an input end of a second power divider (6) is connected with a local oscillator signal LO, a first output end of the second power divider (6) outputs a first local oscillator signal LO1 to a local oscillator port of the first mixer (4), a second output end of the second power divider (6) outputs a second local oscillator signal LO2 to a local oscillator port of the second mixer (5), and an output end of the first power divider (4) outputs a first radio frequency signal RF1 to a first input end of a mixer (7), and an output end of the second power divider (7) outputs a microwave signal RF2 to an RF output end of the second mixer (8).

2. Mixer circuit capable of suppressing 2IF according to claim 1, characterized in that: the first local oscillation signal LO1 and the second local oscillation signal LO2 are in the same frequency and phase.