Broadband anti-interference down-conversion device and radio frequency receiving system

Abstract

The utility model discloses a broadband anti-interference down-conversion device and a radio frequency receiving system, and relates to the wireless communication technology. The device comprises a first frequency converter, a second frequency converter, a power divider and a local oscillator unit. Wherein the first frequency converter and the second frequency converter realize two-stage frequency conversion of radio frequency signals, the second frequency converter adopts a dual-channel ping-pong switching structure, and two channels are connected with the output end of the first frequency converter through the power divider; the local oscillation unit provides independent local oscillation signal input for the first frequency converter, the second frequency converter and the local oscillation unit. According to the utility model, the broadband and high-dynamic interference suppression performance is realized through the combination of two-stage frequency conversion and a dual-channel ping-pong switching structure.

Description

Technical Field

[0001] This utility model relates to the field of wireless communication technology, specifically to a wideband anti-interference downconversion device and a radio frequency receiving system. Background Technology

[0002] With the rapid development of wireless communication, radar detection, and electronic countermeasures technologies, the demand for wide bandwidth coverage, high-frequency adaptability, and dynamic anti-interference performance in radio frequency (RF) receiving systems is becoming increasingly urgent. As the core front-end module of the RF receiving link, the down-conversion device undertakes the critical task of converting high-frequency RF signals into mid-to-low-frequency signals, and its performance directly affects the system's sensitivity, anti-interference capability, and signal processing accuracy. This is especially true in high-frequency applications such as satellite communication and millimeter-wave radar. However, traditional down-conversion architectures face problems such as limited bandwidth, sensitivity to phase noise, and insufficient dynamic interference suppression.

[0003] Traditional single-stage downconverters are limited by the mixer's operating bandwidth and local oscillator frequency range, making it difficult to simultaneously cover the wideband requirements from GHz to tens of GHz. For example, in Ka-band (26.5-40GHz) applications, single-stage mixers often have to sacrifice linearity or noise performance to achieve high-frequency coverage, leading to a decrease in overall system performance. A two-stage conversion architecture can expand the operating bandwidth. For instance, two phase-locked loops can be used to generate two corresponding local oscillators, which are then selected by a switch to output one local oscillator signal. This signal is then mixed with the RF signal to obtain the intermediate frequency (IF) signal. By switching the two local oscillator signals, different frequencies can be obtained. However, phase jumps are prone to occur during local oscillator frequency switching, leading to transient signal distortion and significantly reducing dynamic anti-interference performance.

[0004] In conclusion, the operating bandwidth and anti-interference performance of downconverters in existing satellite communication systems still need further improvement. Utility Model Content

[0005] This invention provides a wideband anti-interference downconverter and radio frequency receiving system, which solves the problems of insufficient operating bandwidth and dynamic interference suppression in existing satellite downconverters.

[0006] This utility model is achieved through the following technical solution:

[0007] In a first aspect, a wideband anti-interference downconverter is provided, comprising:

[0008] The first frequency converter is used to mix the received radio frequency signal with the first local oscillator signal and output the first intermediate frequency signal.

[0009] A power divider, connected to the output of the first frequency converter, is used to divide the first intermediate frequency signal into two paths.

[0010] The second frequency converter includes a first frequency conversion branch, a second frequency conversion branch, and a switching switch. The first frequency conversion branch and the second frequency conversion branch are respectively connected to the two output terminals of the power divider. The first frequency conversion branch is used to mix the first intermediate frequency signal with the second local oscillator signal to output a second intermediate frequency signal. The second frequency conversion branch is used to mix the first intermediate frequency signal with the three local oscillator signals to output a second intermediate frequency signal. The switching switch is used to select whether to output the second intermediate frequency signal from the first frequency conversion branch or the second frequency conversion branch.

[0011] The local oscillator unit is connected to the first frequency converter, the first frequency conversion branch, and the second frequency conversion branch, respectively, and is used to provide the local oscillator signal required for mixing to the first frequency converter, the first frequency conversion branch, and the second frequency conversion branch.

[0012] To address the issues of insufficient bandwidth in single-stage frequency converters and reduced dynamic resistance in two-stage local oscillator switching frequency converters, this invention combines a two-stage frequency converter with a dual-channel ping-pong switching architecture. The first frequency converter mixes and outputs a first intermediate frequency signal, while the second frequency converter mixes and outputs a lower-frequency second intermediate frequency signal, significantly improving anti-interference performance. In the second-stage frequency converter, a dual-channel ping-pong switching structure is employed. The first and second frequency converter branches receive two local oscillator signals from the local oscillator unit, perform independent frequency conversion, and select the output via a switching switch. This avoids nonlinear distortion of the local oscillator signal during frequency switching, thereby widening the operating bandwidth and enhancing the dynamic anti-interference capability of the receiving system.

[0013] In one embodiment, the first frequency converter includes a low-noise amplifier, a bandpass filter, a mixer, an intermediate frequency filter, and an intermediate frequency amplifier connected in sequence, wherein the output of the intermediate frequency amplifier is used as the output of the first frequency converter.

[0014] In one embodiment, both the first frequency conversion branch and the second frequency conversion branch include a bandpass filter, a mixer, an attenuator, and a low-pass filter connected in sequence. The output terminal of the low-pass filter is connected to the switching switch, and the input terminal of the bandpass filter serves as the input terminal of the second frequency converter.

[0015] In one embodiment, the mixer is model HMC8193.

[0016] In one embodiment, the bandpass filter is an adjustable resonant filter.

[0017] In one embodiment, the attenuator is a digitally controlled attenuator HMC624.

[0018] In one embodiment, the local oscillator unit includes a first local oscillator unit, a second local oscillator unit, and a third local oscillator unit. The first local oscillator unit is used to provide a first local oscillator signal, the second local oscillator unit is used to provide a second local oscillator signal, and the third local oscillator unit is used to provide a third local oscillator signal. The second local oscillator unit and the third local oscillator unit employ a common-source phase-locked loop.

[0019] In one embodiment, the local oscillator unit further includes a phase calibration unit, which is integrated with the second local oscillator unit and the third local oscillator unit and is used to perform dynamic phase compensation on the second local oscillator unit and the third local oscillator unit.

[0020] In one embodiment, the switching switch adopts a two-stage three-switch chip series structure, including a first switch chip, a second switch chip and a third switch chip. The first switch chip and the second switch chip are respectively connected in series at the end of the first frequency conversion branch and the second frequency conversion branch, and are connected in series with the third switch chip. The third switch chip is connected in series with the combined output terminal of the first frequency conversion branch and the second frequency conversion branch.

[0021] In a second aspect, a radio frequency receiving system is provided, including a wideband anti-interference downconversion device as described in any one of the first aspects.

[0022] Compared with the prior art, this invention has the following advantages and beneficial effects: Combining a two-stage frequency conversion and a dual-channel ping-pong switching architecture expands the receiver bandwidth and significantly improves anti-interference performance. Because in the second-stage frequency conversion, the first and second frequency conversion branches respectively receive two local oscillator signals provided by the local oscillator unit, perform independent frequency conversion processing, and select the output through a switching switch, nonlinear distortion due to local oscillator signal frequency switching is avoided. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the exemplary embodiments of this utility model, the drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this utility model and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0024] Figure 1 This diagram shows an overall structural schematic of a wideband anti-interference downconverter according to an embodiment of the present invention.

[0025] Figure 2 A schematic diagram of the structure of a first frequency converter according to an embodiment of the present invention is shown;

[0026] Figure 3A schematic diagram of the structure of a second frequency converter according to an embodiment of the present invention is shown;

[0027] Figure 4 A schematic diagram of a switching switch according to an embodiment of the present invention is shown. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this utility model are only used to explain this utility model and are not intended to limit this utility model.

[0029] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims, and accompanying drawings of this utility model are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to other steps or units inherent in the device.

[0030] The terminology used in the various embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the various embodiments of this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of this application pertain. The terms (such as those defined in a generally used dictionary) are to be interpreted as having the same meaning as in the context of the relevant technical field and are not to be interpreted as having an idealized or overly formal meaning, unless clearly defined in the various embodiments of this application.

[0031] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to implement the present invention. In other embodiments, well-known structures, circuits, materials, or methods are not specifically described in order to avoid obscuring the present invention.

[0032] To address the limitations of traditional single-stage downconverters in simultaneously covering wideband requirements from GHz to tens of GHz due to the constraints of mixer operating bandwidth and local oscillator frequency range, and the issue that two-stage frequency conversion structures using fixed intermediate frequency are prone to phase jumps during local oscillator switching, leading to transient signal distortion, this invention provides a wideband anti-interference downconverter device and receiving system to improve the dynamic anti-interference performance of the system while achieving a wideband operating bandwidth.

[0033] Please see Figure 1 , Figure 1The diagram illustrates a wideband anti-interference downconverter device according to an embodiment of this utility model, comprising a first inverter, a second inverter, a local oscillator unit, and a power divider. The second inverter employs a dual-channel ping-pong switching design, including a first inverter branch, a second inverter branch, and a switching switch. The first and second inverter branches are connected in parallel, with the rear ends of both branches connected to the switching switch. The switching switch selects whether the first or second inverter branch is active; that is, when the switching switch is active on the first inverter branch, the inverter signal of the first inverter branch is output; when the switching switch is active on the second inverter branch, the inverter signal of the second inverter branch is output, thus achieving the dual-channel ping-pong switching design.

[0034] The first frequency converter is used as the first stage of frequency conversion, and the second frequency converter is used as the second stage of frequency conversion. The first and second frequency converters are connected through a power divider. The power divider splits the frequency conversion signal output from the first frequency converter into two paths. The two outputs of the power divider are respectively connected to the two frequency conversion branches of the second frequency converter, and are sent to the first or second frequency conversion branch for the second stage of frequency conversion.

[0035] The local oscillator unit includes a first local oscillator unit, a second local oscillator unit, and a third local oscillator unit, which independently provide different local oscillator signals to the first frequency converter and the first frequency converter's second frequency conversion branch, respectively. The first frequency converter is connected to the first local oscillator unit, and mixes the received radio frequency signal from the antenna with the first local oscillator signal provided by the first local oscillator unit to output a first intermediate frequency (IF) signal. The first frequency conversion branch is connected to the second local oscillator unit, and mixes the received first IF signal with the second local oscillator signal provided by the second local oscillator unit to output a second IF signal. The second frequency conversion branch is connected to the third local oscillator unit, and mixes the received first IF signal with the third local oscillator signal provided by the third local oscillator unit to output a second IF signal. After two stages of down-mixing, the frequency of the second IF signal output by the second mixer is lower than that of the first IF signal. The second IF signal is then filtered and demodulated by the back-end circuitry to obtain the baseband signal.

[0036] In this embodiment, the second frequency converter does not use a local oscillator signal switching design. Instead, it provides local oscillator inputs to two branches through a second and third local oscillator unit, respectively. A switching switch at the back end selects one intermediate frequency (IF) signal for output, enabling frequency switching. In this embodiment, when the phase-locked loop (PLL) of the first branch locks onto the corresponding local oscillator signal, it mixes with the radio frequency (RF) signal through the mixer of that branch to output the corresponding IF signal. At this time, the switch switches to the IF signal output by the first branch. Simultaneously, the PLL of the second branch begins receiving a new frequency word and locks onto it within the required switching time. It then mixes with the RF signal to output the corresponding IF signal, and the switch switches to the IF signal output by the second branch. There is no bandpass filter in the path after the switching switch, therefore the output signal does not exhibit trailing or oscillation phenomena. Compared to directly switching the local oscillator signal frequency, the entire system can achieve full channel backup functionality except for the switching time. Both the frequency hopping time and frequency switching time meet the specifications, avoiding signal transient distortion problems during the period before and after local oscillator frequency switching.

[0037] In one embodiment, the device further includes a power supply module, which is connected to the first frequency converter, the second frequency converter, and the local oscillator unit respectively, for supplying power to the first frequency converter, the second frequency converter, and the local oscillator unit respectively.

[0038] In one implementation, see Figure 2 As shown, the first frequency converter includes a low-noise amplifier, a bandpass filter, a mixer, an intermediate frequency filter, and an intermediate frequency amplifier connected in sequence, with the output of the intermediate frequency amplifier serving as the output of the first frequency converter.

[0039] The low-noise amplifier (LNA) receives the RF signal from the antenna and amplifies the weak RF signal, contributing to noise suppression in subsequent modules. The ADL5523 filter chip can be used as an option. The bandpass filter suppresses out-of-band interference and image frequencies; a cavity filter can be used. The mixer mixes the RF signal with the first local oscillator (LO1) and down-converts it to the first intermediate frequency (IF). The HMC8193 (0.1-10GHz) or ADL5801 (for high frequencies) can be used as an option. The IF filter removes harmonics and spurious signals after mixing, such as LO1 leakage and sum-frequency components. A SAW filter (100MHz center frequency, 20MHz bandwidth) can be used as an option. The IF amplifier compensates for mixing and filtering losses and provides sufficient drive capability. A variable gain amplifier, such as the ADL5243 (100MHz bandwidth, 0-30dB gain range), is preferred.

[0040] In one implementation, see Figure 3As shown, both the first and second frequency conversion branches include a bandpass filter, a mixer, an attenuator, and a low-pass filter connected in sequence. The input terminal of the bandpass filter serves as the input terminal of the second frequency converter and is connected to the two outputs of the power divider. The output terminal of the low-pass filter is connected to a switching switch.

[0041] The bandpass filter is designed to remove spurious and out-of-band noise from the first-stage frequency conversion, preventing interference signals from entering the secondary mixer. A cavity filter or an LC lumped filter can be used, with the center frequency set as the first intermediate frequency (IF) and a bandwidth slightly larger than the signal bandwidth. The mixer mixes the first IF signal IF1 with the ping-pong local oscillator (second IF signal LO2A / third IF signal LO2B), outputting the second IF signal IF2. An HMC8193 or ADL5801 can be used. The attenuator can be a fixed attenuator or a digitally controlled attenuator HMC624. The low-pass filter removes the sum-frequency components and high-frequency spurious signals generated during mixing.

[0042] In one implementation, the bandpass filter is selected as an adjustable resonant filter.

[0043] In one embodiment, the local oscillator unit includes a first local oscillator unit, a second local oscillator unit, and a third local oscillator unit. The first local oscillator unit is used to provide a first local oscillator signal, the second local oscillator unit is used to provide a second local oscillator signal, and the third local oscillator unit is used to provide a third local oscillator signal. The second local oscillator unit and the third local oscillator unit employ a common-source phase-locked loop to ensure the phase continuity of the second local oscillator signal and the third local oscillator signal.

[0044] In one embodiment, the local oscillator unit further includes a phase calibration unit, which is integrated with the second and third local oscillator units. The phase calibration unit can perform dynamic phase compensation on the second and third local oscillator units. Specifically, the phase calibration unit uses a digital phase detector and an adjustable delay line. When the switching switch selects different frequency conversion branches, the phase detector compares the phase difference between the two local oscillator signals in real time and performs dynamic phase compensation through the adjustable delay line.

[0045] In one implementation, such as Figure 4 As shown, the switching switch adopts a two-stage three-switch chip series structure, including a first switch chip, a second switch chip, and a third switch chip. The first and second switch chips are connected in series at the end of the first and second frequency conversion branches, respectively, and are also connected in series with the third switch chip. The third switch chip is connected in series with the combined output terminal of the first and second frequency conversion branches. The ADRF5020 switch chip can be selected as one of the switch chips.

[0046] An embodiment of this utility model also provides a radio frequency receiving system, which includes the wideband anti-interference downconversion device of any of the above embodiments of this utility model.

[0047] An embodiment of this utility model also provides a radio frequency transceiver system, which includes a radio frequency receiving module and a radio frequency transmitting module. The radio frequency receiving module includes the wideband anti-interference downconversion device of any of the above embodiments of the utility model.

[0048] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A wideband anti-interference downconverter, characterized in that, include: The first frequency converter is used to mix the received radio frequency signal with the first local oscillator signal and output the first intermediate frequency signal. A power divider, connected to the output of the first frequency converter, is used to divide the first intermediate frequency signal into two paths. The second frequency converter includes a first frequency conversion branch, a second frequency conversion branch, and a switching switch. The first frequency conversion branch and the second frequency conversion branch are respectively connected to the two output terminals of the power divider. The first frequency conversion branch is used to mix the first intermediate frequency signal with the second local oscillator signal to output the second intermediate frequency signal. The second frequency conversion branch is used to mix the first intermediate frequency signal with the three local oscillator signals to output the second intermediate frequency signal. The switching switch is used to select whether to output the second intermediate frequency signal from the first frequency conversion branch or the second frequency conversion branch. The local oscillator unit is connected to the first frequency converter, the first frequency conversion branch, and the second frequency conversion branch, respectively, and is used to provide the local oscillator signal required for mixing to the first frequency converter, the first frequency conversion branch, and the second frequency conversion branch.

2. The wideband anti-interference downconverter according to claim 1, characterized in that, The first frequency converter includes a low-noise amplifier, a bandpass filter, a mixer, an intermediate frequency filter, and an intermediate frequency amplifier connected in sequence, and the output of the intermediate frequency amplifier is used as the output of the first frequency converter.

3. The wideband anti-interference downconverter according to claim 1, characterized in that, Both the first and second frequency conversion branches include a bandpass filter, a mixer, an attenuator, and a low-pass filter connected in sequence. The output of the low-pass filter is connected to the switching switch, and the input of the bandpass filter serves as the input of the second frequency converter.

4. The wideband anti-interference downconverter according to claim 2 or 3, characterized in that, The mixer is model HMC8193.

5. The wideband anti-interference downconverter according to claim 3, characterized in that, The bandpass filter is an adjustable resonant filter.

6. The wideband anti-interference downconverter according to claim 3, characterized in that, The attenuator is a digitally controlled attenuator HMC624.

7. The wideband anti-interference downconverter according to claim 1, characterized in that, The local oscillator unit includes a first local oscillator unit, a second local oscillator unit, and a third local oscillator unit. The first local oscillator unit is used to provide a first local oscillator signal, the second local oscillator unit is used to provide a second local oscillator signal, and the third local oscillator unit is used to provide a third local oscillator signal. The second local oscillator unit and the third local oscillator unit adopt a common source phase-locked loop.

8. The wideband anti-interference downconverter according to claim 7, characterized in that, The local oscillator unit further includes a phase calibration unit, which is integrated with the second local oscillator unit and the third local oscillator unit and is used to perform dynamic phase compensation on the second local oscillator unit and the third local oscillator unit.

9. The wideband anti-interference downconverter according to claim 1, characterized in that, The switching switch adopts a two-stage three-switch chip series structure, including a first switch chip, a second switch chip and a third switch chip. The first switch chip and the second switch chip are respectively connected in series at the end of the first frequency conversion branch and the second frequency conversion branch, and are connected in series with the third switch chip. The third switch chip is connected in series with the combined output terminal of the first frequency conversion branch and the second frequency conversion branch.

10. A radio frequency receiving system, characterized in that, Includes the wideband anti-interference downconverter as described in any one of claims 1-9.

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