Broadband intermediate frequency processing circuit and control method thereof
By combining a dual-channel intermediate frequency processing scheme and a fine filter, the problems of signal distortion and phase noise in broadband signal measurement of the spectrum analyzer are solved, achieving smooth bandwidth switching and low power consumption design, and improving the stability and energy efficiency of signal processing.
Patent Information
- Application Number
- CN202511322591.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-16
- Publication Date
- 2026-01-23
AI Technical Summary
Existing spectrum analyzers suffer from signal distortion, phase noise degradation, and excessive system power consumption when measuring broadband signals. Traditional filter banks struggle to achieve smooth wide/narrow band switching.
A dual-channel intermediate frequency (IF) processing scheme is adopted, including broadband and narrowband IF channels. A combination of broadband and narrowband filters is used, along with independently enabled amplifiers, to achieve fine signal processing and amplification control. The circuit design is optimized to ensure signal stability and low power consumption.
It effectively solves the signal distortion problem, improves phase noise performance, achieves smooth wide/narrow band switching, reduces system power consumption, and improves the accuracy and energy efficiency of signal processing.
Smart Images
Figure CN121396110A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of electronic measurement technology, in particular to a wideband intermediate frequency processing circuit and a control method thereof. BACKGROUND
[0002] With the technical progress of electronic measuring instruments and long-term technical accumulation, more and more enterprises enter this field, and the market competition is increasingly fierce. The development of electronic measuring instruments is like the development of multifunctional direction. The latest spectrum analyzer on the market currently supports sweep mode, real-time spectrum mode and network parameter measurement function. With the expansion of the function of the spectrum analyzer, the bottleneck of the current intermediate channel processing circuit is also more and more obvious. For example, when the spectrum analyzer measures the coexistence of strong and weak signals in a wideband signal, the signal distortion is serious; the traditional filter bank is difficult to realize smooth wide / narrow band switching; the use of multiple amplifiers leads to excessive power consumption of the system; and the phase noise is deteriorated when processing a wideband signal. SUMMARY
[0003] To solve the problems mentioned in the background, the purpose of the present application is to provide a wideband intermediate frequency processing circuit and a control method thereof.
[0004] In the first aspect, the purpose of the present application can be realized by the following technical scheme: a wideband intermediate frequency processing circuit, comprising:
[0005] A channel switching switch is used to switch the wideband and narrowband of the analog intermediate frequency signal running path;
[0006] A channel switch is used to switch the intermediate frequency channel, wherein the intermediate frequency channel comprises a first channel, a second channel, a third channel and a fourth channel;
[0007] A wideband filter is used to filter and process a 307.2MHz wideband intermediate frequency signal, retain a 100MHz effective bandwidth, suppress out-of-band interference signals, and meet the application scenarios of high bandwidth;
[0008] A narrowband filter is used to filter and process a 288MHz narrowband intermediate frequency signal, retain a 5MHz effective bandwidth, provide high selectivity filtering, improve the out-of-band suppression effect, and meet the fine signal processing;
[0009] An amplifier is used to amplify the analog intermediate frequency signal, and the gain of the amplifier can be adjusted according to the signal output from the front end, so as to control the amplitude of the intermediate frequency signal and ensure that the final output is a stable intermediate frequency signal meeting the sampling requirements of the ADC.
[0010] In some implementations of the first aspect, the circuit further comprises: the channel switch S1 and S2 as a switch between wideband and narrowband, i.e., a two-way switch, when S1 and S2 are switched to the wideband filter, the signal goes through the wideband path, the center frequency of the signal is 307.2 MHz, and the maximum analog bandwidth is 100 MHz; when S1 and S2 are switched to the narrowband filter, the signal goes through the narrowband path, the center frequency of the signal is 290 MHz, and the maximum analog bandwidth is 5 MHz.
[0011] In some implementations of the first aspect, the circuit further comprises: the channel switch S3 and S4 as a four-way switch, when S3 and S4 are switched to the first channel, the intermediate frequency gain is 0 dB, when S3 and S4 are switched to the second channel, the intermediate frequency gain is 10 dB, when S3 and S4 are switched to the third channel, the intermediate frequency gain is 20 dB, and when S3 and S4 are switched to the fourth channel, the intermediate frequency gain is 30 dB, thereby achieving a gain adjustment of 0-30 dB.
[0012] In some implementations of the first aspect, the circuit further comprises: the wideband mode adopts a direct decimation processing, and the 100 MHz wideband is reserved; and the narrowband mode adopts a combination of a SAW filter and a 7th order LC elliptical filter, and the 5 MHz bandwidth is reserved.
[0013] In some implementations of the first aspect, the circuit further comprises: the amplifiers AMP1-AMP5 are provided with independent enable control pins, when the signal does not go through the path of the related amplifier, the related amplifier is disabled, and is in a low-power consumption mode, thereby reducing the system power consumption.
[0014] In some implementations of the first aspect, the circuit further comprises: the wideband filters BPF1 and BPF3 are designed by using LC elliptical filters, the center frequency is 307.2 MHz, the bandwidth is 100 MHz, and the out-of-band rejection is >55 dB@±150 MHz.
[0015] In some implementations of the first aspect, the circuit further comprises: the narrowband filter BPF2 is designed by using a surface acoustic wave filter, the center frequency is 288 MHz, the bandwidth is 5 MHz, and the out-of-band rejection is >75 dB@±10 MHz.
[0016] In some implementations of the first aspect, the circuit further comprises: the analog intermediate frequency signal is converted into a digital signal by a high-speed ADC after being processed by the conditioning circuit, and then is subjected to a series of digital processing in the FPGA, including DDC, decimation filtering, FIR forming filter, FFT operation, video filtering, and detection.
[0017] In a second aspect, to achieve the above object, the application discloses a control method of a wideband intermediate frequency processing circuit, which comprises the following steps: setting the initial state of the device, detecting user settings and setting the timeout waiting time, when detecting that there is a user setting parameter, entering the next step of judging the working mode; confirming the working mode of the device according to the user settings, which is divided into a real-time spectrum mode and a sweep spectrum mode, when it is the real-time spectrum mode, setting the intermediate frequency bandwidth of the device as a wideband mode to adapt to the bandwidth requirement of real-time spectrum analysis; when it is the sweep spectrum mode, setting the corresponding wideband mode by obtaining the sweep width, which is divided into a wideband intermediate frequency and a narrowband intermediate frequency mode; obtaining the reference level, the radio frequency attenuator and the preamplifier parameters; setting the corresponding gain position according to the obtained parameters; detecting the over-range and obtaining the ADC data, when detecting the over-range, setting the gain position as the appropriate position, and outputting the over-range indication.
[0018] The beneficial effects of the application are as follows:
[0019] Effectively solve the signal distortion problem:
[0020] The application adopts a dual-channel intermediate frequency processing scheme, including a wideband (307.2 MHz) and a narrowband (288 MHz) intermediate frequency channel. For a wideband signal, 100 MHz wideband is reserved by direct extraction processing, which can completely capture and transmit various information in the wideband signal, avoiding distortion caused by mutual interference of strong and weak signals; for a narrowband signal, a SAW filter + 7th order LC elliptical filter combination is adopted, which reserves a 5 MHz bandwidth, and can accurately process specific narrowband signals, further reducing interference, thereby effectively solving the signal distortion problem in wideband signal measurement, and ensuring high precision and high quality of signal processing.
[0021] Improve the phase noise performance:
[0022] The application optimizes the circuit design and adopts appropriate filters, amplifiers and other components to finely process and optimize the signal, significantly improves the phase noise performance of wideband signal processing, makes the signal more stable and reliable, and provides a good foundation for subsequent signal analysis and measurement.
[0023] Realize smooth wide / narrow band switching:
[0024] The innovative circuit design of the application makes the wide / narrow band switching smooth. When it is needed to switch from wide band mode to narrow band mode, or vice versa, the system can select the corresponding path according to the working mode, i.e. wide band mode selects wide band filter and corresponding amplifier path, narrow band mode selects narrow band filter and corresponding amplifier path, and through reasonable circuit layout and control logic, the continuity and stability of the signal in the switching process are ensured, and problems such as signal interruption, mutation, etc. do not occur, which provides convenience for the rapid switching of electronic measuring instruments under different measurement requirements.
[0025] Multi-stage amplification system optimization:
[0026] The application contains five amplifiers (AMP1-AMP5) and has independent enable control pins. The amplifiers can be selectively enabled / disabled according to the signal path, and the related amplifiers are automatically disabled in the path where the signal does not pass through, avoiding unnecessary energy consumption. At the same time, through this flexible amplifier control mode, the use of amplifiers can be reasonably adjusted according to the actual signal strength and processing requirements, which not only ensures that the signal can be properly amplified and processed, but also reduces the overall power consumption of the system and improves the energy utilization efficiency of the system. BRIEF DESCRIPTION OF DRAWINGS
[0027] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, a brief introduction will be given below to the drawings needed to be used in the embodiments or prior art description, and obviously, other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings;
[0028] Figure 1 is a schematic diagram of the overall framework of the application;
[0029] Figure 2 is a schematic diagram of the intermediate frequency signal path in the application;
[0030] Figure 3 is a schematic diagram of the wide band filter in the application;
[0031] Figure 4 is a schematic diagram of the narrow band filter in the application;
[0032] Figure 5 is a schematic diagram of the LMX2572 phase-locked loop circuit design in the application;
[0033] Figure 6 is a schematic diagram of the control method flow in the application. DETAILED DESCRIPTION
[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.
[0035] Embodiment one:
[0036] As shown in the figure, a wideband intermediate frequency processing circuit comprises: Figure 1
[0037] Channel switching switch: used for mutual switching of wideband and narrowband for the analog intermediate frequency signal running path;
[0038] Channel switch: used for switching of an intermediate frequency channel, wherein the intermediate frequency channel comprises a first channel, a second channel, a third channel and a fourth channel;
[0039] Wideband filter: used for filtering processing of a 307.2MHz wideband intermediate frequency signal, retaining a 100MHz effective bandwidth, suppressing out-of-band interference signals and meeting a high-bandwidth application scenario;
[0040] Narrowband filter: used for filtering processing of a 288MHz narrowband intermediate frequency signal, retaining a 5MHz effective bandwidth, providing high-selectivity filtering, improving out-of-band suppression effect and meeting fine signal processing;
[0041] Amplifier: used for amplifying an analog intermediate frequency signal, which can adjust the gain of the amplifier according to the signal output by the front end, thereby controlling the amplitude of the intermediate frequency signal and guaranteeing that the final output is a stable intermediate frequency signal meeting the ADC sampling requirement.
[0042] The channel switching switches S1 and S2 are switching switches for wideband and narrowband, which are two-choice switches. When S1 and S2 are switched to the wideband filter, the signal runs a wideband path at this time, the signal center frequency is 307.2MHz and the maximum analog bandwidth is 100MHz. When S1 and S2 are switched to the narrowband filter, the signal runs a narrowband path at this time, the signal center frequency is 290MHz and the maximum analog bandwidth is 5MHz.
[0043] The channel switches S3 and S4 are four-choice switches. When the switches S3 and S4 are switched to the first channel, the intermediate frequency gain is 0dB at this time. When the switches S3 and S4 are switched to the second channel, the intermediate frequency gain is 10dB at this time. When the switches S3 and S4 are switched to the third channel, the intermediate frequency gain is 20B at this time. When the switches S3 and S4 are switched to the fourth channel, the intermediate frequency gain is 30dB at this time, realizing 0-30dB gain adjustment.
[0044] The wideband mode adopts direct extraction processing, and 100MHz wideband is reserved; the narrowband mode adopts SAW filter and 7-order LC elliptical filter combination filtering, and 5MHz bandwidth is reserved.
[0045] The amplifiers AMP1-AMP5 have independent enable control pins, when the signal does not pass through the path of the related amplifier, the related amplifier is disabled, in a low power consumption mode, thereby reducing system power consumption.
[0046] The wideband filters BPF1 and BPF3 are designed by using LC elliptical filters, the center frequency is 307.2MHz, the bandwidth is 100MHz, and the out-of-band suppression is >55dB@±150MHz.
[0047] The narrowband filter BPF2 is designed by using a surface acoustic wave filter, the center frequency is 288MHz, the bandwidth is 5MHz, and the out-of-band suppression is >75dB@±10MHz.
[0048] The analog intermediate frequency signal is converted into a digital signal by high-speed ADC after the conditioning circuit, and then a series of digital processing such as DDC, extraction filtering, FIR filter, FFT operation, video filtering and detection is carried out in the FPGA.
[0049] The intermediate frequency 100MHz reference clock is provided by the radio frequency module, and a 245.76MHz signal is output by frequency synthesis chip LMX2572 as an ADC sampling clock and an internal main clock of the FPGA.
[0050] The wideband intermediate frequency circuit core device is designed by using xilinx XC7Z030 chip, the FPGA and ARM9 dual-core processor are integrated in the chip, the PL end resource configuration and the PS end cooperative processing are configured.
[0051] The gain control system is composed of digital attenuator and fixed gain amplifier, seamless switching of four gain gears is realized, and the switching time is <1us.
[0052] Embodiment two: in order to achieve the above purpose, based on the basis of embodiment one, the application discloses a control method of a wideband intermediate frequency processing circuit, the method comprises the following steps:
[0053] The initial state of the device is set, the user setting is detected and the timeout waiting time is set, when the user setting parameter is detected, the next step of judging the working mode is entered; the working mode entered by the device is confirmed according to the user setting, which is divided into real-time spectrum mode and sweep spectrum mode, when it is the real-time spectrum mode, the intermediate frequency bandwidth of the device is set as a wideband mode to adapt to the bandwidth requirement of real-time spectrum analysis; when it is the sweep spectrum mode, the corresponding wideband mode is set through the acquisition of the sweep width, which is divided into wideband intermediate frequency and narrowband intermediate frequency modes; the reference level, radio frequency attenuator and preamplifier parameters are acquired; the corresponding gain gear is set according to the acquired parameters; the over-range is detected and the ADC data is acquired, when the over-range is detected, the gain gear is set as the appropriate gear, and the over-range indication is output.
[0054] Based on the same inventive concept, the application further provides a computer device, comprising: one or more processors, and a memory for storing one or more computer programs; the program comprises program instructions, and the processor is configured to execute the program instructions stored in the memory. The processor can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc., which are the computing core and control core of the terminal, and are configured to implement one or more instructions, and are specifically configured to load and execute one or more instructions in the computer storage medium to implement the above method.
[0055] It should be further noted that based on the same inventive concept, the present application further provides a computer storage medium, which stores a computer program, and the computer program is run by a processor to execute the above method. The storage medium can adopt any combination of one or more computer readable media. The computer readable medium can be a computer readable signal medium or a computer readable storage medium. The computer readable storage medium may, for example, but is not limited to, an electrical, magnetic, optical, electrical, magnetic, infrared, or semiconductor system, device or apparatus, or any combination thereof. More specific examples (non-exhaustive list) of the computer readable storage medium include: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present application, the computer readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, device or apparatus.
[0056] In the description of the present application, the description of the terms "one embodiment", "an example", "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.
[0057] The basic principles, main features and advantages of the present disclosure are shown and described above. It should be understood by those skilled in the art that the present disclosure is not limited by the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principles of the present disclosure. Without departing from the spirit and scope of the present disclosure, various changes and improvements can be made to the present disclosure, and these changes and improvements all fall within the scope of the claimed present disclosure.
Claims
1. A wideband intermediate frequency processing circuit, characterized by It comprises: Channel switching switch: for mutual switching of wideband and narrowband of analog intermediate frequency signal running path; Channel switch: for switching intermediate frequency channel, wherein the intermediate frequency channel comprises a first channel, a second channel, a third channel and a fourth channel; Wideband filter: for filtering processing of 307.2MHz wideband intermediate frequency signal, retaining 100MHz effective bandwidth, suppressing out-of-band interference signal, and meeting high bandwidth application scenario; Narrowband filter: for filtering processing of 288MHz narrowband intermediate frequency signal, retaining 5MHz effective bandwidth, providing high selectivity filtering, and improving out-of-band suppression effect to meet fine signal processing; Amplifier: for amplifying analog intermediate frequency signal, which can adjust the gain of the amplifier according to the signal output by the front end, so as to control the amplitude of the intermediate frequency signal and ensure that the final output is a stable intermediate frequency signal meeting the sampling requirements of ADC.
2. A wideband intermediate frequency processing circuit according to claim 1, characterized in that The channel switching switch S1 and S2 are switching switches for wideband and narrowband, and are two-choice switches. When S1 and S2 are switched to the wideband filter, the signal runs in the wideband path, the signal center frequency is 307.2MHz, and the maximum analog bandwidth is 100MHz. When S1 and S2 are switched to the narrowband filter, the signal runs in the narrowband path, the signal center frequency is 288MHz, and the maximum analog bandwidth is 5MHz.
3. A wideband intermediate frequency processing circuit according to claim 1, wherein, The channel switch S3 and S4 are four-choice switches. When the switch S3 and S4 are switched to the first channel, the intermediate frequency gain is 0dB. When the switch S3 and S4 are switched to the second channel, the intermediate frequency gain is 10dB. When the switch S3 and S4 are switched to the third channel, the intermediate frequency gain is 20B. When the switch S3 and S4 are switched to the fourth channel, the intermediate frequency gain is 30dB, realizing 0-30dB gain adjustment.
4. A wideband intermediate frequency processing circuit according to claim 2, wherein, The wideband mode adopts direct decimation processing, retaining 100MHz wideband, and the narrowband mode adopts SAW filter and 7-order LC elliptical filter combination filtering, retaining 5MHz bandwidth.
5. A wideband intermediate frequency processing circuit according to claim 1, wherein, The amplifiers AMP1-AMP5 have independent enable control pins. When the signal does not pass through the path of the related amplifier, the related amplifier is disabled and in low power consumption mode, thereby reducing system power consumption.
6. A wideband intermediate frequency processing circuit according to claim 1, wherein, The wideband filters BPF1 and BPF3 are designed by using LC elliptical filter, the center frequency is 307.2MHz, the bandwidth is 100MHz, and the out-of-band suppression is >55dB@±150MHz.
7. A wideband intermediate frequency processing circuit according to claim 1, wherein, The narrowband filter BPF2 is designed by using acoustic surface filter, the center frequency is 288MHz, the bandwidth is 5MHz, and the out-of-band suppression is >75dB@±10MHz.
8. A wideband intermediate frequency processing circuit according to claim 1, wherein, The analog intermediate frequency signal is converted into digital signal by high-speed ADC after the conditioning circuit, and then a series of digital processing such as DDC, decimation filtering, FIR filter, FFT operation, video filtering and detection is carried out in the FPGA.
9. A control method of a wideband intermediate frequency processing circuit, characterized by, The method comprises the following steps: The initial state of the device is set, the user setting is detected and the timeout waiting time is set, when the user setting parameter is detected, the next step of judging the working mode is entered; the working mode entered by the device is confirmed according to the user setting, which is divided into real-time spectrum mode and sweep spectrum mode, when it is the real-time spectrum mode, the intermediate frequency bandwidth of the device is set as a wideband mode to adapt to the bandwidth requirement of real-time spectrum analysis; When it is the sweep spectrum mode, the corresponding wideband mode is set by acquiring the sweep width, which is divided into wideband intermediate frequency and narrowband intermediate frequency modes; the reference level, the radio frequency attenuator and the preamplifier parameters are acquired; the corresponding gain position is set according to the acquired parameters; the over-range is detected and the ADC data is acquired, when the over-range is detected, the gain position is set as a suitable position, and the over-range indication is output.