WO2018054152A1

WO2018054152A1 - Down-conversion device

Info

Publication number: WO2018054152A1
Application number: PCT/CN2017/093247
Authority: WO
Inventors: 陈家诚; 范丛明; 姚建可; 丁庆
Original assignee: 华讯方舟科技有限公司; 深圳市华讯方舟卫星通信有限公司
Priority date: 2016-09-26
Filing date: 2017-07-18
Publication date: 2018-03-29
Also published as: CN106253855B; CN106253855A

Abstract

A down-conversion device, comprising a PCB board (10), as well as a high-frequency amplification module (110), a local oscillation module (120), a filtering module (130), a frequency mixing module (140), an intermediate-frequency amplification module (150), and a direct current bias module (160) which are attached on the PCB board (10). The high-frequency amplification module (110) is used for performing multi-stage amplification modulation on high-frequency signals received from a satellite. The local oscillation module (120) is used for performing amplification modulation on generated local oscillation signals. The filtering module (130) is used for down-converting the processed high-frequency signals and the local oscillation signals into intermediate-frequency signals in the frequency mixing module (140), and the intermediate-frequency signals are amplified and then output to a post-modem. The down conversion device adopts a modular design concept of attaching various function modules to the PCB board (10), and has advantages of circuit miniaturization and high level of integration. Moreover, the direct current bias module (160) can also provide a direct current bias voltage to the high-frequency amplification module (110), the local oscillation module (120), and the intermediate-frequency amplification module (150). Therefore, electronic components in the bias module (160) are reduced, the occupied area of the PCB board (10) is reduced, and the cost of the down conversion device is effectively reduced.

Description

Downconverter

Technical field

The present invention relates to the field of satellite communication technology, and more particularly to a downconversion device operating in the Ka band.

Background technique

In recent years, based on the advantages of large bandwidth transmission capacity and market demand, the market demand for multi-band communication satellites or full Ka-band communication satellites is increasing. The Ka band is mainly 26.5 to 40 GHz, which greatly increases the bandwidth of communication. The use of Ka-band broadband satellites will become the industry trend for satellite broadband communications in the future. Correspondingly, the ground terminal market has also achieved great development, and the number of satellite terminals used has reached one million. The terminal equipment of the ground station is an indispensable part of the Ka-band satellite network.

Among them, the transceiver device is the communication core part of the ground station. The down-conversion module in the signal receiving portion is used for amplifying, down-converting, and down-converting the high-frequency Ka-band signal emitted from the satellite to the intermediate-frequency L-band signal, and then performing subsequent processing through the modem. The traditional signal receiving part uses a plurality of complicated discrete components, which is relatively large in size and high in cost.

Summary of the invention

Based on this, it is necessary to provide a downconversion device with high integration, small size, and low cost in response to the above problems.

A down conversion device includes: a PCB board and a board mounted on the PCB board:

a high frequency amplification module for performing multistage amplification modulation on a high frequency signal received from a satellite and outputting;

The local oscillator module is configured to generate a local oscillator signal and amplify the output;

The filtering module is respectively connected to the high frequency amplifying module and the local oscillator module, and is configured to filter the high frequency signal and the local oscillator signal respectively;

a mixing module, configured to be coupled to the filtering module, configured to perform mixing processing on the high frequency signal and the local oscillator signal processed by the filtering module, and output an intermediate frequency signal;

An intermediate frequency amplification module, coupled to the mixing module, for modulating an amplified output of the intermediate frequency signal; as well as

The DC biasing module is respectively connected to the high frequency amplifying module, the local oscillator module, and the intermediate frequency amplifying module, and is configured to provide a DC bias voltage for the high frequency amplifying module, the local oscillator module, and the intermediate frequency amplifying module.

In one embodiment, the high frequency amplification module includes a first low noise amplifier, a second low noise amplifier, and a third low noise amplifier which are cascaded in three stages, wherein the first low noise amplifier and the second low The noise amplifier and the third low noise amplifier are both transistor amplifiers.

In one embodiment, the high frequency amplification module further includes a first capacitor and a second capacitor;

The first capacitor is connected in series between the first low noise amplifier and the second low noise amplifier, and the second capacitor is connected in series between the second low noise amplifier and the third low noise amplifier.

In one embodiment, the DC biasing module includes a DC bias chip and a plurality of triode active biasing units;

The DC bias chip is configured to provide a gate bias and a drain bias voltage for the transistor amplifier, and is also configured to provide a positive and negative bias voltage for a plurality of the active bias units;

One of the triode active biasing units biases one of the low noise amplifiers.

In one embodiment, two of the triode active bias units bias the first transistor amplifier and the second transistor amplifier; the DC bias chip biases the third transistor amplifier .

In one embodiment, the DC bias chip is further configured to provide a DC bias voltage to the local oscillator module and the intermediate frequency amplification module.

In one embodiment, the local oscillator module includes a local oscillator generator and a fourth low noise amplifier;

The local oscillator generator is coupled to a fourth low noise amplifier for generating a local oscillator signal, and the fourth low noise amplifier amplifies and modulates the local oscillator signal.

In one embodiment, the filtering module includes a first filtering unit and a second filtering unit; the first filtering unit is respectively connected to the high frequency amplifying module and the mixing module, and is configured to Performing filtering; the second filtering unit is respectively connected to the local oscillator module and the mixing module, and configured to filter the local oscillator signal.

In one embodiment, the first filtering unit and the second filtering unit are parallel coupled microstrip line bandpass filters.

In one embodiment, the mixing module is one of a single balanced mixer, a double balanced mixer, and a second harmonic mixing chip.

The above-mentioned down-conversion device includes: a PCB board and a high-frequency amplification module, a local oscillator module, a filter module, a mixing module, an intermediate frequency amplification module, and a DC bias module mounted on the PCB board. The high-frequency amplification module performs multi-stage amplification modulation on the high-frequency signal received from the satellite and sends it to the filtering module to perform filtering processing on the corresponding band. The local oscillator module amplifies and modulates the generated local oscillator signal and sends it to the filtering module for filtering of the corresponding band. After processing, the high-frequency signal and the local oscillator signal processed by the filtering module are down-converted to an intermediate frequency signal by mixing processing by the mixing module, and the intermediate frequency signal is amplified by the intermediate frequency amplification module and output to the modem of the subsequent stage. The down-conversion device adopts a modular design idea, and the functional modules are attached to the PCB board by a simple surface mount technology, which has the advantages of miniaturization and high integration of the circuit. At the same time, the DC bias module can also provide DC bias voltage for the high frequency amplification module, the local oscillator module and the intermediate frequency amplification module, which reduces the number of electronic components used in the bias module and reduces the area occupied by the PCB board. While meeting the performance requirements, the cost of the downconversion device can be effectively reduced.

DRAWINGS

1 is a structural block diagram of a down conversion device of an embodiment;

2 is a circuit diagram of a down converter of an embodiment;

3 is a schematic structural diagram of a mixing module in an embodiment;

4 is a layout diagram of a DC bias chip pin in an embodiment;

Figure 5 is a circuit diagram of a triode active bias unit in an embodiment.

detailed description

In order to facilitate the understanding of the present invention, the invention will be described more fully hereinafter with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the understanding of the present disclosure will be more fully understood.

All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Terms used in the description of the invention herein It is intended to be only illustrative of specific embodiments and is not intended to limit the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.

As shown in FIG. 1, the structural frame diagram of the down-conversion device can be used in a receiver in the Ka-band, Ku-band, and X-band. In this embodiment, the down-conversion device is used in a Ka-band receiver, wherein the down-conversion device includes a PCB board 10, a high-frequency amplification module 110 mounted on the PCB board 10, a local oscillator module 120, and a filter module 130. The mixing module 140, the intermediate frequency amplifying module 150, and the DC biasing module 160.

The high frequency amplifying module 110 performs multi-stage amplification modulation on the high frequency signal received from the satellite and sends it to the filtering module 130 for filtering processing in the corresponding band. The local oscillator module 120 amplifies and modulates the generated local oscillator signal and sends the local oscillator signal to the filtering module 130. The filtering process of the corresponding band, the high-frequency signal and the local oscillator signal processed by the filtering module 130 are down-converted to the intermediate frequency signal by the mixing processing by the mixing module 140, and the intermediate frequency signal is amplified by the intermediate frequency amplifying module 150 and output to the modem of the subsequent stage. in. The down-converting device is a key device for receiving signals in the transceiver, and the high-frequency amplifying module 110, the local oscillator module 120, the filtering module 130, the mixing module 140, the intermediate frequency amplifying module 150, and the DC biasing module 160 are all surface-applied with a simple process. The mounting of the technical mounting on the PCB board 10 eliminates the process steps of wire bonding, has low cost, and has the advantages of miniaturization of the circuit and high integration. At the same time, the DC bias module 160 can also provide a DC bias voltage for the high frequency amplification module 110, the local oscillator module 120, and the intermediate frequency amplification module 150. The number of electronic components used in the bias module is reduced, and the area occupied by the PCB board is small, and the cost of the down-conversion device can be effectively reduced while satisfying performance requirements, so that the down-conversion device has the advantage of miniaturization.

The PCB board 10 is a high-frequency PCB board 10. In the embodiment, the high-frequency PCB board 10 uses a ceramic substrate, and the ROGERS 4350 series is selected. In other embodiments, the ROGERS 4003 series, the 5880 series, etc. may also be selected, or A high-frequency PCB board 10 of a polytetrafluoroethylene plate (PTFE) can be selected according to actual needs.

Referring to FIG. 2, the high frequency amplification module 110 is configured to perform multi-stage amplification modulation on a high frequency signal received from a satellite and output. In the present embodiment, the high frequency amplification module 110 includes a first low noise amplifier M1, a second low noise amplifier M2, a third low noise amplifier M3, a first capacitor C1, and a second capacitor C2 that are cascaded in three stages. The first capacitor C1 is connected in series between the first low noise amplifier M1 and the second low noise amplifier M2, and the second capacitor C2 is connected in series between the second low noise amplifier M2 and the third low noise amplifier M3. Each level of low noise amplifiers is cascaded by DC blocking capacitors (C1, C2), so that the DC offset of each stage of the low noise amplifier does not affect each other. Low Noise Amplifier (LNA) is commonly used as a high frequency or intermediate frequency preamplifier for all types of radio receivers and as an amplifying circuit for high sensitivity electronic detection equipment. In the case of amplifying a weak signal, the noise of the amplifier itself is reduced to interfere with the signal to improve the signal-to-noise ratio of the output. In this embodiment, the first low noise amplifier M1, the second low noise amplifier M2, the third low noise amplifier M3, the transistor amplifier, and the transistor amplifier are all high electron mobility transistors (HEMT) of the gallium arsenide process. In other embodiments, it may also be a Field Effect Transistor (FET), a Heterojunction Bipolar Transistor (HBT), or a Metal-Semiconductor Field Effect Transistor (Metal-Semiconductor). FET) or Junction Field-Effect Transistor (JFET).

The local oscillator module 120 is configured to generate a local oscillator signal and amplify the output. The local oscillator module 120 includes a local oscillator generator U1 and a fourth low noise amplifier M4; the local oscillator generator U1 is connected to the fourth low noise amplifier M4, and the local oscillator generator U1 is used to generate a local oscillator signal, and the fourth low noise Amplifier M4 amplifies and modulates the local oscillator signal. In this embodiment, the local oscillator signal is generated by a surface mount technology microwave local oscillator generating chip, and the microwave local oscillator generating signal ranges from 9.03 to 9.22 GHz, and the local oscillator signal applied to the Ka-band down-conversion device is used. The frequency is 9.125 GHz. Among them, the microwave generating chip is generated by a local oscillator source of a phase locked loop. The fourth low noise amplifier M4 amplifies the generated local oscillation signal, wherein the fourth low noise amplifier M4 can be of the same type as the low noise amplifier in the high frequency amplification module 110 described above. In other embodiments, the local oscillator signal can also be generated by using a Dielectric oscillator. If the local oscillator is used to generate the local oscillator signal, the fourth low noise amplifier M4 can be omitted.

The local oscillator generator U1 is attached to the PCB board 10 by surface mount technology, and no need to adjust or modify the frequency on the production line, which is convenient for manufacturing, and the design introduction is simple and the cost is low. In this embodiment, the local oscillator generator U1 can be fabricated by a silicon germanium:carbon (SiGe:C) process technology, which has good noise characteristics, strong radio frequency performance, good reliability, and lower power consumption; in other embodiments It can also be made by using gallium arsenide process or gallium nitride process technology.

The filtering module 130 is respectively connected to the high frequency amplifying module 110 and the local oscillator module 120, and is configured to perform filtering processing on the high frequency signal and the local oscillator signal respectively. The filtering module 130 includes the first The filtering unit 131 and the second filtering unit 135. The first filtering unit 131 is respectively connected to the high frequency amplifying module 110 and the mixing module 140, and is configured to filter the high frequency signal, and output the filtered high frequency signal to the mixing module 140; the second filtering unit 135 respectively The local oscillator module 120 and the mixing module 140 are connected to filter the local oscillator signal, and output the filtered local oscillator signal to the mixing module 140.

In this embodiment, the first filtering unit 131 and the second filtering unit 133 are all parallel coupled microstrip line bandpass filters. Parallel coupled microstrip linepass filter is formed on PCB board 10 by copper plating or copper plating plus silver plating. The thickness is 17μm～34μm (0.5 oz-1 oz), which can increase the parallel coupled microstrip line bandpass filter. The filtering effect of the device can also be performed by using a conventional electroplating device for the copper plating process. The local oscillator signal generated by the local oscillator generator U1 has a frequency range of 9.03 to 9.22 GHz, and the local oscillator signal amplifies the local oscillation signal through the fourth low noise amplifier M4 and passes through the first filtering unit 131 to have a center frequency of 9.125 GHz. As the local oscillator input of the mixing module 140. The high frequency signal received by the high frequency module has a frequency range of 19.2 to 20.2 GHz, and the high frequency signal passes through the multistage amplification modulation and passes through the second filtering unit 135 to pass the high frequency signal of the sub-band as the high frequency of the mixing module 140. Input.

The mixing module 140 is configured to receive the high frequency signal processed by the filtering module 130, the local oscillator signal mixing process, and output the intermediate frequency signal. In this embodiment, the mixing module 140 is a single balanced mixer, and the high frequency signal and the local oscillator signal pass through a single balanced mixer to generate an intermediate frequency signal output. Among them, the single balanced mixer uses two parallel-connected Schottky diodes, which constitute a second harmonic mixer. The IF signal output end is the same port as the local oscillator signal input end. In an embodiment, the method further includes a low-pass filtering network connected to the mixing module 140, and the intermediate frequency signal is outputted by the low-pass filtering network to output an intermediate frequency signal having a frequency of 950 MHz to 1450 MHz.

In other embodiments, the mixing module 140 can also be a double balanced mixer, a second harmonic mixing chip, or the like. In the case of a second harmonic mixing chip, the second harmonic mixing chip is a Monolithic Microwave Integrated Circuit (MMIC) chip fabricated by a gallium arsenide (GaAs) process. The second harmonic mixing chip is also mounted on the PCB 10 by surface mount technology (SMT), which eliminates the process steps of wire bonding.

The intermediate frequency amplifying module 150 is connected to the mixing module 140 for modulating and amplifying the output of the intermediate frequency signal. In this embodiment, the intermediate frequency amplifying module 150 includes a two-stage intermediate frequency amplifier, and the intermediate frequency signal is amplified by a two-stage intermediate frequency amplifier to obtain a required intermediate frequency signal, which is output to the modem. In other real In the embodiment, only the first-level intermediate frequency amplifier is used in the intermediate frequency amplifying module 150, which can reduce the cost, but does not affect the amplification effect of the intermediate frequency signal.

The DC biasing module 160 is connected to the high frequency amplifying module 110, the local oscillator module 120, and the intermediate frequency amplifying module 150, and is configured to provide a DC bias voltage for the high frequency amplifying module 110, the local oscillator module 120, and the intermediate frequency amplifying module 150.

The DC bias module 160 includes a DC bias chip U2 and a plurality of transistor active bias units 161.

The DC bias chip U2 is used to provide a gate bias, a drain bias voltage for the transistor amplifier, and a positive and negative bias voltage for the plurality of active bias cells. The DC bias chip U2, referring to FIG. 3, includes a plurality of sets of correspondingly disposed gate bias pins and drain bias pins, and a positive voltage output terminal V _OUT and a negative voltage for supplying a voltage to the transistor active bias unit 161 Output V _ENG . Wherein, the drain bias pin D provides a positive voltage to the gate of the transistor amplifier, and the gate bias pin G provides a negative voltage to the drain of the transistor amplifier. In this embodiment, the DC bias chip U2 includes four sets of correspondingly disposed gate bias pins (G1, G2, G3, G4) and drain bias pins (D1, D2, D3, D4). There is a set of positive voltage output terminals V _OUT and negative voltage output terminals V _{ENG that} supply voltage to the triode active bias unit 161. Since the drain voltage of a transistor amplifier operating in the Ka band is 2V, the gate is generally negative. In the present embodiment, the drain bias pin D of the DC bias chip U2 outputs a positive voltage of 2 volts, and the gate bias pin G has a negative voltage of -0.6 volts.

A triode active bias unit 161 biases a first stage low noise amplifier (transistor amplifier), wherein a gate of the transistor amplifier is respectively connected to a negative voltage supply terminal of the triode active bias unit 161 and a collector of the triode; The drain of the transistor amplifier is respectively connected to the positive voltage supply terminal of the triode active bias unit 161 and the emitter of the triode; the source of the transistor amplifier is grounded. Transistor active bias unit 161 is capable of providing the transistor amplifier with the required positive bias voltage and negative bias voltage to operate the transistor amplifier at the optimum operating conditions of drain voltage V _DS = 2V, I _DS = 10mA. At the same time, the triode active bias unit 161 also acts to stabilize the current, so that the transistor amplifier obtains a stable DC state.

In one embodiment, the first low noise amplifier M1 and the second low noise amplifier M2 in the high frequency amplification module 110 are respectively biased by a triode active bias unit 161; The amplifier M3 is biased by the DC bias chip U2. Specifically, the positive voltage output ends of the DC bias chip U2 are respectively connected to the positive voltage power supply ends of the two transistor active bias units 161. The negative voltage output terminals of the DC bias chip U2 are respectively connected to the negative voltage supply terminals of the two transistor active bias units 161. The gate bias pin of the DC bias chip U2 is coupled to the drain of the third transistor amplifier to provide a positive voltage. The drain bias pin of the DC bias chip U2 is coupled to the gate of the third transistor amplifier to provide a negative voltage.

The first low noise amplifier M1 and the second low noise amplifier M2 all use the same active DC bias, and the transistor amplifier is DC-biased through the triode, which can ensure the first low noise amplifier M1 and the second low noise amplifier M2. Good DC working condition, but also has a certain temperature stability. The third low noise amplifier M3 is biased by a DC bias chip U2, which directly outputs the gate and drain bias voltages required by the third low noise amplifier M3, while also providing a positive voltage to the transistor. The negative voltage simplifies the circuit design and reduces the PCB area and cost while satisfying the performance of the noise figure of the first low noise amplifier M1 and the second low noise amplifier M2.

In one embodiment, the triode active bias unit 161 and the second low noise amplifier M2 that bias the first low noise amplifier M1 can be integrated with the two transistors of the bias transistor active bias unit 161. Together, form a component. Its integrated components can be replaced with a PNP universal dual transistor (NXP/PUMT1), which simplifies the use of electronic components and reduces the PCB footprint. The third low noise amplifier M3 is biased by the DC bias chip U2, and the bias portion of the third low noise amplifier M3 is performed while ensuring the noise performance of the first low noise amplifier M1 and the second low noise amplifier M2. Simplify design processing, which allows the overall design to guarantee performance while saving design costs and material costs while saving PCB area.

In one embodiment, the first low noise amplifier M1, the second low noise amplifier M2, and the third low noise amplifier M3 in the high frequency amplification module 110 are respectively biased by a triode active bias unit 161.

In one embodiment, the first low noise amplifier M1 in the high frequency amplification module 110 is biased by a triode active bias unit 161; the second low noise amplifier M2 and the third low noise amplifier M3 are simultaneously performed. Offset is the DC bias chip U2.

In one embodiment, the DC bias chip U2 is further used for the local oscillator module 120 and the intermediate frequency amplification module. Block 150 provides a DC bias voltage. The local oscillator module 120 includes a local oscillator generator U1 and a fourth low noise amplifier M4. The positive voltage output terminal of the DC bias chip U2 can supply power to the local oscillator generator U1, and the DC bias chip U2 can also be the fourth. The low noise amplifier M4 provides a drain, gate bias voltage that is biased. Of course, the fourth low noise amplifier M4 can also be actively biased using an active triode bias unit. The DC bias chip U2 can also be used to provide a corresponding bias voltage to the gate and drain of the intermediate frequency amplifier in the intermediate frequency amplification module 150.

The DC biasing module 160 is connected to the high frequency amplifying module 110, the local oscillator module 120, and the intermediate frequency amplifying module 150, and is configured to provide a DC bias voltage for the high frequency amplifying module 110, the local oscillator module 120, and the intermediate frequency amplifying module 150. The entire PCB is compact in layout and simple in circuit design, which can reduce the cost and design cost of the downconversion device, and the modular design in the downconversion device facilitates later maintenance and overhaul.

The technical features of the above-described embodiments may be arbitrarily combined. For the sake of brevity of description, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction between the combinations of these technical features, All should be considered as the scope of this manual.

The above-described embodiments are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but is not to be construed as limiting the scope of the invention. It should be noted that a number of variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the invention should be determined by the appended claims.

Claims

A down conversion device, comprising: a PCB board and mounted on the PCB board:

a high frequency amplification module for performing multistage amplification modulation on a high frequency signal received from a satellite and outputting;

The local oscillator module is configured to generate a local oscillator signal and amplify the output;

The filtering module is respectively connected to the high frequency amplifying module and the local oscillator module, and is configured to filter the high frequency signal and the local oscillator signal respectively;

a mixing module, configured to be coupled to the filtering module, configured to perform mixing processing on the high frequency signal and the local oscillator signal processed by the filtering module, and output an intermediate frequency signal;

An intermediate frequency amplification module, coupled to the mixing module, for modulating an amplified output of the intermediate frequency signal;

The DC biasing module is respectively connected to the high frequency amplifying module, the local oscillator module, and the intermediate frequency amplifying module, and is configured to provide a DC bias voltage for the high frequency amplifying module, the local oscillator module, and the intermediate frequency amplifying module.
The down conversion apparatus according to claim 1, wherein the high frequency amplification module comprises a first stage low noise amplifier, a second low noise amplifier, and a third low noise amplifier which are cascaded in three stages, wherein the A low noise amplifier, a second low noise amplifier, and a third low noise amplifier are all transistor amplifiers.
The down conversion device according to claim 2, wherein the high frequency amplification module further comprises a first capacitor and a second capacitor;

The first capacitor is connected in series between the first low noise amplifier and the second low noise amplifier, and the second capacitor is connected in series between the second low noise amplifier and the third low noise amplifier.
The downconversion device according to claim 2, wherein the DC biasing module comprises a DC bias chip and a plurality of triode active biasing units;

The DC bias chip is configured to provide a gate bias and a drain bias voltage for the transistor amplifier, and is also configured to provide a positive and negative bias voltage for a plurality of the active bias units;

One of the triode active biasing units biases one of the low noise amplifiers.
A downconversion device according to claim 4, wherein two of said triodes are active The bias unit correspondingly biases the first transistor amplifier and the second transistor amplifier; the DC bias chip biases the third transistor amplifier.
The down converter device according to claim 4, wherein the DC bias chip is further configured to provide a DC bias voltage to the local oscillator module and the intermediate frequency amplification module.
The down converter device according to claim 1, wherein the local oscillator module comprises a local oscillator generator and a fourth low noise amplifier;

The local oscillator generator is coupled to a fourth low noise amplifier for generating a local oscillator signal, and the fourth low noise amplifier amplifies and modulates the local oscillator signal.
The down conversion apparatus according to claim 1, wherein the filtering module comprises a first filtering unit and a second filtering unit; wherein the first filtering unit is respectively connected to the high frequency amplifying module and the mixing module, And filtering the high frequency signal; the second filtering unit is respectively connected to the local oscillator module and the mixing module, and configured to filter the local oscillator signal.
The down conversion apparatus according to claim 8, wherein the first filtering unit and the second filtering unit are parallel coupled microstrip line band pass filters.
The down conversion apparatus according to claim 1, wherein the mixing module is one of a single balanced mixer, a double balanced mixer, and a second harmonic mixing chip.