Variable intermediate frequency wideband receiving system and method

Abstract

This application discloses a variable intermediate frequency (IF) broadband receiving system and method, relating to the field of wireless communication technology. The system includes: an RF front-end module for receiving RF signals within a preset frequency band; a control module connected to the RF front-end module, a variable IF generation module, and an IF conditioning module, for generating a second local oscillator signal and setting the bandwidth control signal of the adjustable filter in the IF conditioning module based on the target instantaneous bandwidth; a variable IF generation module connected to the RF front-end module for mixing the RF signal with the second local oscillator signal to generate a variable IF signal; and an IF conditioning module connected to the variable IF generation module for filtering the variable IF signal using the adjustable filter to obtain the target IF signal. This application aims to solve the technical problems of poor bandwidth adaptability and severe nonlinear distortion accumulation in traditional fixed IF receivers.

Description

Technical Field

[0001] This application relates to the field of wireless communication technology, and in particular to a variable intermediate frequency broadband receiving system and method. Background Technology

[0002] In communication, radar, and other systems, receivers need to process wideband radio frequency signals ranging from shortwave to millimeter wave. Traditional receivers typically employ a fixed intermediate frequency (IF) architecture, processing the radio frequency signal by down-converting it to a fixed IF.

[0003] However, the intermediate frequency (IF) and filter bandwidth used in traditional receivers are fixed during the hardware design phase, which cannot simultaneously meet the different requirements of narrowband to ultra-wideband signals. In addition, the fixed multi-stage mixing links used by traditional receivers to process high-frequency signals accumulate severe nonlinear distortion, causing in-band interference when processing high-power signals. Summary of the Invention

[0004] The main objective of this application is to provide a variable intermediate frequency broadband receiving system and method, which aims to solve the technical problems of poor bandwidth adaptability and severe accumulation of nonlinear distortion in traditional fixed intermediate frequency receivers.

[0005] To achieve the above objectives, this application provides a variable intermediate frequency (IF) broadband receiving system, comprising: a radio frequency (RF) front-end module, a variable IF generation module, an IF conditioning module, and a control module; the RF front-end module is used to receive RF signals within a preset frequency band; the control module is connected to the RF front-end module, the variable IF generation module, and the IF conditioning module respectively, and is used to generate a second local oscillator signal and set the bandwidth control signal of the adjustable filter in the IF conditioning module based on the target instantaneous bandwidth; the variable IF generation module is connected to the RF front-end module and is used to mix the RF signal with the second local oscillator signal to generate a variable IF signal; the IF conditioning module is connected to the variable IF generation module and includes an adjustable filter, and the IF conditioning module uses the adjustable filter to filter the variable IF signal to obtain a target IF signal.

[0006] Optionally, the variable intermediate frequency (IF) generation module includes: a second mixer, a local oscillator (LO) spurious suppression circuit, and an adjustable filter circuit; the second mixer is used to receive the second LO signal and mix the radio frequency (RF) signal with the second LO signal to generate an initial variable IF signal; the LO spurious suppression circuit is connected to the second mixer and is used to suppress LO leakage spurious signals in the initial variable IF signal to generate a purified variable IF signal; the adjustable filter circuit is connected to the LO spurious suppression circuit and is used to perform bandpass filtering on the purified variable IF signal to output a variable IF signal.

[0007] Optionally, the system further includes: a first mixing module; the control module is also connected to the first mixing module and is used to generate a first local oscillator signal and to generate a control level based on the frequency of the radio frequency signal, the control level being used to control the activation and deactivation of the first mixing module; the first mixing module is used to receive the control level and, when the radio frequency signal is a low-frequency signal, to mix the radio frequency signal with the first local oscillator signal to generate a first intermediate frequency signal; the output terminal of the first mixing module is connected to the variable intermediate frequency generation module, the variable intermediate frequency generation module being further used to mix the first intermediate frequency signal with the second local oscillator signal to generate a variable intermediate frequency signal when the radio frequency signal is a low-frequency signal.

[0008] Optionally, the first mixing module includes: a first mixer, a fourth amplifier, a fourth filter, a fifth filter, a sixth filter, a first switch, and a second switch; the input terminal of the first mixer is connected to the output terminal of the RF front-end module through the first switch, for receiving a first local oscillator signal, and mixing the RF signal with a preset first local oscillator signal to generate an initial first intermediate frequency signal when the RF signal is a low-frequency signal; the fourth filter is connected to the first mixer, for filtering out spurious signals in the initial first intermediate frequency signal; the fourth amplifier is connected to the fourth filter, for performing gain compensation on the filtered initial first intermediate frequency signal; the fifth filter is connected to the fourth amplifier, for filtering the gain-compensated initial first intermediate frequency signal to obtain a first intermediate frequency signal; one end of the second switch is connected to the fifth filter, and the other end is connected to the output terminal of the first mixing module, and the control level is used to control the opening and closing of the first switch and the second switch; the input terminal of the sixth filter is connected to the output terminal of the RF front-end module, for filtering the RF signal when the RF signal is not a low-frequency signal.

[0009] Optionally, the system further includes: a first mixing module, the first mixing module including a first mixer, a seventh filter, and an eighth filter; the control module is also connected to the first mixing module, used to generate a first local oscillator signal, and to generate a switch control signal based on the frequency band of the radio frequency signal, and to determine a target filter from the seventh filter and the eighth filter based on the switch control signal; the input terminal of the first mixer is connected to the output terminal of the radio frequency front-end module, used to mix the radio frequency signal with the first local oscillator signal to generate an adjusted first intermediate frequency signal; the seventh filter and the eighth filter are both connected to the first mixer, used to filter the adjusted first intermediate frequency signal based on the target filter to obtain a first intermediate frequency signal; the output terminal of the first mixing module is connected to the variable intermediate frequency generation module, the variable intermediate frequency generation module is also used to mix the first intermediate frequency signal with the second local oscillator signal to generate a variable intermediate frequency signal.

[0010] Optionally, the system further includes: a second mixing module; the control module is also connected to the second mixing module for generating a third local oscillator signal; the input terminal of the second mixing module is connected to the intermediate frequency conditioning module for mixing the target intermediate frequency signal with the third local oscillator signal to generate and output the final intermediate frequency signal when the frequency difference between the target intermediate frequency signal and the preset target signal is greater than a preset threshold.

[0011] Optionally, the RF front-end module includes a limiter, an adjustable amplifier, a first filter, a first attenuator, and a second filter; the limiter is used to clamp the power of instantaneous high-power signals in the RF signal; the adjustable amplifier is connected to the limiter and is used to amplify the RF signal when the power of the RF signal is less than a preset power threshold; the first filter is connected to the adjustable amplifier and is used to filter the amplified RF signal; the first attenuator is connected to the limiter and is used to perform fixed attenuation of the RF signal when the power of the RF signal is greater than or equal to a preset power threshold; the second filter is connected to the first attenuator and is used to filter the attenuated RF signal.

[0012] Optionally, the second mixing module includes a third mixer; the third mixer is used to mix the target intermediate frequency signal with the third local oscillator signal when the frequency difference between the target intermediate frequency signal and the preset target signal is greater than a preset threshold.

[0013] Optionally, the first mixer module further includes: a fifth amplifier and a ninth filter; the input terminal of the fifth amplifier is connected to the output terminal of the seventh filter and the output terminal of the eighth filter, and is used to perform gain compensation on the filtered adjusted first intermediate frequency signal; the ninth filter is connected to the fifth amplifier and is used to filter the gain-compensated adjusted first intermediate frequency signal to suppress out-of-band noise.

[0014] Furthermore, to achieve the above objectives, this application also provides a variable intermediate frequency (IF) broadband receiving method, which applies the above system and includes: receiving a radio frequency (RF) signal within a preset frequency band; generating a second local oscillator (LO) signal and setting a bandwidth control signal for an adjustable filter in the IF conditioning module based on a target instantaneous bandwidth; mixing the RF signal with the second LO signal to generate a variable IF signal; and filtering the variable IF signal using the adjustable filter to obtain a target IF signal.

[0015] This application proposes a variable intermediate frequency (IF) broadband receiving system and method. First, a control module dynamically generates a second local oscillator (LO) signal frequency based on the frequency band of the input radio frequency (RF) signal. A variable IF generation module then mixes the LO signal with the input RF signal, allowing the center frequency of the system's output variable IF signal to be flexibly configured over a wide range. This overcomes the frequency adaptability problem of traditional fixed IF architectures, enabling the receiver to handle signals across the entire frequency band from low to high frequencies. Second, this application uses a control module to dynamically set the bandwidth of the adjustable filter in the IF conditioning module based on the target instantaneous bandwidth. This allows the receiving channel to accurately match the actual bandwidth requirements of signals from different systems, such as narrowband and broadband. While effectively extracting the target signal, it maximally suppresses in-band noise and adjacent channel interference, solving the problem that fixed-bandwidth filters cannot simultaneously adapt to signals with multiple bandwidths. Attached Figure Description

[0016] Figure 1 This is one of the structural block diagrams of the variable intermediate frequency broadband receiving system provided in the embodiments of this application; Figure 2 This is a structural block diagram of the radio frequency front-end module provided in the embodiments of this application; Figure 3 This is a structural block diagram of the variable intermediate frequency generation module provided in the embodiments of this application; Figure 4 This is a structural block diagram of the local oscillator spurious suppression circuit provided in an embodiment of this application; Figure 5 This is a structural block diagram of the intermediate frequency conditioning module provided in an embodiment of this application; Figure 6 A structural block diagram of an intermediate frequency conditioning module, including the internal structure of the control module, provided in an embodiment of this application; Figure 7This is the second structural block diagram of the variable intermediate frequency broadband receiving system provided in the embodiments of this application; Figure 8 This is one of the structural block diagrams of the first mixer module provided in the embodiments of this application; Figure 9 This is one of the simulation diagrams of mixing nonlinear spurious signals provided in the embodiments of this application; Figure 10 This is the second simulation diagram of mixing nonlinear spurious emissions provided in the embodiments of this application; Figure 11 The third structural block diagram of the variable intermediate frequency broadband receiving system provided in the embodiments of this application; Figure 12 This is a second structural block diagram of the first mixer module provided in the embodiments of this application; Figure 13 This is a structural block diagram of the second mixer module provided in an embodiment of this application; Figure 14 This is the third simulation diagram of mixing nonlinear spurious emissions provided in the embodiments of this application; Figure 15 A flowchart illustrating the variable intermediate frequency broadband receiving method provided in this application embodiment.

[0017] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0019] In communication, radar, and other systems, receivers need to process wideband radio frequency signals ranging from shortwave to millimeter wave. Traditional receivers typically employ a fixed intermediate frequency (IF) architecture, processing the radio frequency signal by down-converting it to a fixed IF.

[0020] However, the intermediate frequency (IF) and filter bandwidth used in traditional receivers are fixed during the hardware design phase, which cannot simultaneously meet the different requirements of narrowband to ultra-wideband signals. Furthermore, the fixed multi-stage mixer links used in traditional receivers suffer from fixed gain distribution and difficulty in optimizing the noise figure when receiving high-frequency signals. In addition, fixed multi-stage mixer links accumulate severe nonlinear distortion, causing in-band interference when traditional receivers process high-power signals.

[0021] To address the shortcomings of traditional fixed intermediate frequency (IF) receivers, existing technologies mostly focus on localized improvements at the hardware level. For example, using a fixed IF filter with higher bandwidth can expand the instantaneous bandwidth, but its bandwidth expansion capability is limited by device manufacturing processes, and it cannot be specifically optimized for the filtering characteristics of signals in different frequency bands. Another example is using multiple sets of parallel fixed IF channels, which can cover multiple frequency points, but it significantly increases the system hardware complexity and cost, and still cannot achieve continuous and flexible configuration across the entire frequency band. Yet another example is using a high-speed ADC to directly sample RF signals, which simplifies the analog link, but is limited by the analog input bandwidth (typically ≤2GHz) and sampling rate of current ADC chips, making it difficult to directly acquire and process ultra-wideband signals.

[0022] In summary, to solve the above problems, this application provides a variable intermediate frequency broadband receiving system and method, and the solution of this application will be described in detail below.

[0023] Figure 1 This is one of the structural block diagrams of a variable intermediate frequency (IF) broadband receiving system provided in the embodiments of this application. The variable IF broadband receiving system 100 may include: a control module 110, a radio frequency front-end module 120, a variable IF generation module 130, and an IF conditioning module 140.

[0024] The radio frequency (RF) front-end module 120 can receive RF signals within a preset frequency band. The control module 110 is connected to the RF front-end module 120, the variable intermediate frequency (IF) generation module 130, and the IF conditioning module 140. The control module 110 can generate a second local oscillator signal and set the bandwidth control signal of the adjustable filter in the IF conditioning module 140 based on the target instantaneous bandwidth. The variable IF generation module 130 is connected to the RF front-end module 120 and can mix the RF signal with the second IF signal to generate a variable IF signal. The IF conditioning module 140 is connected to the variable IF generation module 130 and includes an adjustable filter. The IF conditioning module 140 can use the adjustable filter to filter the variable IF signal to obtain the target IF signal. It should be noted that the second IF signal can be determined based on the frequency band of the externally input RF signal.

[0025] In this embodiment, please refer to Figure 2 , Figure 2 A structural block diagram of an RF front-end module 120 is shown. The RF front-end module 120 may include: an antenna (not shown), a limiter, an adjustable amplifier, a first filter, a first attenuator, and a second filter.

[0026] The system includes an antenna for receiving externally input radio frequency (RF) signals, a limiter for clamping instantaneous high power in the RF signals to protect downstream circuitry, an adjustable amplifier connected to the limiter for low-noise amplification of the signal to set the initial gain and noise figure of the system, a first filter connected to the adjustable amplifier, a second filter for bandpass filtering of the RF signals to suppress out-of-band interference, a first attenuator connected to the limiter for fixed attenuation of the RF signals, and a second filter connected to the first attenuator for filtering the attenuated RF signals.

[0027] It is understood that the adjustable amplifier can be a low-noise amplifier, and the second filter can be a bandpass filter. In this embodiment, the initial gain is set to 15dB to 20dB, and the noise figure is less than or equal to 2dB.

[0028] In the specific implementation process, the input radio frequency (RF) signal first passes through a limiter for power protection. Then, a power threshold is set, and the RF signal is divided into two paths for processing according to its power. When the power of the RF signal is less than the power threshold, the RF signal passes through an adjustable amplifier and a first filter in sequence to complete low-noise amplification and filtering, and outputs the pre-processed RF signal. When the power of the RF signal is greater than or equal to the power threshold, the RF signal passes through a first attenuator and a second filter in sequence to complete fixed attenuation and filtering, and outputs the pre-processed RF signal.

[0029] In this embodiment, please refer to Figure 3 , Figure 3 A structural block diagram of a variable intermediate frequency (IF) generation module 130 is shown. The variable IF generation module 130 may include: a second mixer, a local oscillator spurious suppression circuit, an adjustable filter circuit, a first amplifier, and a third filter.

[0030] The second mixer receives the second local oscillator signal LO2 generated by the control module 110 and mixes the radio frequency signal with the second local oscillator signal LO2 to generate an initial variable intermediate frequency (IF) signal. A local oscillator spurious suppression circuit is connected to the second mixer and is used to suppress local oscillator leakage spurious signals in the initial variable IF signal to generate a purified variable IF signal. An adjustable filter circuit is connected to the local oscillator spurious suppression circuit and is used to perform bandpass filtering on the purified variable IF signal to output a filtered variable IF signal. A first amplifier is connected to the adjustable filter circuit and is used to adjust the amplitude of the filtered variable IF signal to stabilize its output signal power within a preset range. A third filter is connected to the first amplifier and is used to filter the gain-adjusted radio frequency signal to suppress out-of-band noise and harmonics that may be introduced by the first amplifier and output a variable IF signal.

[0031] In the specific implementation process, the control module 110 can dynamically configure a frequency-adjustable second local oscillator source according to the frequency band of the input RF signal through a digital interface (such as SPI) to generate a second local oscillator signal LO2. The second mixer mixes the input RF signal with the second local oscillator signal LO2, and outputs a target variable intermediate frequency signal (IF2=|RF-LO2|, with a range set to 100MHz~1.8GHz, where RF in this embodiment refers to the input RF signal) and various mixing spurious signals. The local oscillator spurious signal suppression circuit suppresses mixing spurious components caused by local oscillator leakage. Subsequently, under the instruction of the control module, the adjustable filter circuit adjusts its bandwidth to match the target instantaneous bandwidth of the RF signal (for example, selecting a bandwidth of 10~50MHz for a 10MHz narrowband signal and a bandwidth of 500MHz~1GHz for a 1GHz wideband signal), and extracts the target variable intermediate frequency signal IF2.

[0032] It should be noted that in this embodiment, the frequency of the second local oscillator signal and the bandwidth of the adjustable filter circuit are both controlled by the control module.

[0033] For example, please refer to Figure 4 , Figure 4 A block diagram of a local oscillator spurious suppression circuit is shown. The local oscillator spurious suppression circuit may include: a second mixer (and... Figure 3 (The second mixer is the same as the first directional coupler, the second directional coupler, the second amplifier, the fourth filter, the phase shifter, and the second attenuator.)

[0034] The second mixer receives the second local oscillator signal and mixes the radio frequency signal with the second local oscillator signal to generate an initial variable intermediate frequency signal. The first directional coupler couples the second local oscillator signal out of the local oscillator link, first amplifies it through the second amplifier, then performs phase shifting and amplitude control through the phase shifter and the second attenuator according to the preset calibration algorithm, and finally feeds it into the main link through the second directional coupler.

[0035] This embodiment explains the working principle of the local oscillator stray suppression circuit as follows: Suppose that the second local oscillator signal leaked in the main link at this time is a sinusoidal signal with frequency F, amplitude A, and phase φ. :

[0036] The signal fed into the main link through the second directional coupler can be:

[0037] Will and Two signals superimposed:

[0038] At this point, the stray leakage from the local oscillator is eliminated.

[0039] In this embodiment, please refer to Figure 5 , Figure 5 A structural block diagram of an intermediate frequency conditioning module 140 is shown. The intermediate frequency conditioning module 140 may include a third attenuator, an adjustable filter, and a third amplifier.

[0040] The third attenuator is used to receive the variable intermediate frequency (IF) signal and perform step attenuation on the IF signal according to the instructions of the control module. The adjustable filter is connected to the third attenuator. The adjustable filter can dynamically adjust its center frequency and bandwidth according to the instructions of the control module to match the frequency and instantaneous bandwidth of the IF signal, thereby suppressing in-band noise and adjacent channel interference. The third amplifier is connected to the adjustable filter. The third amplifier can provide stable gain for the filtered IF signal and compensate for fixed losses in the link.

[0041] It should be noted that the bandwidth of the adjustable filter can be set according to the target instantaneous bandwidth preset by the implementer.

[0042] In addition, the control module in this embodiment may include an MCU control circuit, a power processing circuit and a clock circuit, and is provided with an external electrical connector for communication with the host computer and access to an external power supply.

[0043] Please see Figure 6 , Figure 6 A schematic diagram of a variable intermediate frequency broadband receiving system, including the internal structure of a control module, is shown. Figure 6 As shown, the MCU control circuit can receive and parse instructions from the host computer through an external electrical connector. It can also configure the frequency of the phase-locked loop of the second local oscillator through a digital interface based on the preset target variable intermediate frequency signal IF2 and radio frequency signal RF, thereby dynamically setting the second local oscillator signal LO2, where IF2=|RF-LO2|. The circuit also runs an automatic gain control algorithm, which can adjust the attenuation value of the third attenuator in the intermediate frequency conditioning module in real time according to the feedback signal.

[0044] The power supply processing circuit is responsible for providing a stable operating voltage to each module in the system. Its input terminal is connected to an external power supply via an external electrical connector. By performing voltage regulation and filtering on the input voltage, it can supply power to the circuit units in each module, ensuring the overall stability of the system.

[0045] The clock circuit can provide a low-phase-noise reference clock signal for the system. This reference clock signal is synchronously transmitted to each module to ensure that the signals across the entire link have consistent frequency accuracy and phase when processing radio frequency signals.

[0046] This application proposes a variable intermediate frequency (IF) broadband receiving system. First, a control module dynamically generates a second local oscillator (LO) signal frequency based on the frequency band of the input radio frequency (RF) signal. A variable IF generation module then mixes the LO signal with the input RF signal, allowing the center frequency of the output variable IF signal to be flexibly configured over a wide range. This overcomes the frequency adaptability problem of traditional fixed IF architectures, enabling the receiver to handle full-band signals from low to high frequencies. Second, this application uses a control module to dynamically set the bandwidth of the adjustable filter in the IF conditioning module based on the target instantaneous bandwidth. This allows the receiving channel to accurately match the actual bandwidth requirements of signals from different systems, such as narrowband and broadband. While effectively extracting the target signal, it maximally suppresses in-band noise and adjacent channel interference, solving the problem that fixed-bandwidth filters cannot simultaneously adapt to multiple bandwidth signals.

[0047] Please see Figure 7 , Figure 7 This is the second structural block diagram of the variable intermediate frequency broadband receiving system provided in the embodiments of this application. It can be understood that... Figure 7 for Figure 1 In a preferred embodiment, the variable intermediate frequency broadband receiving system 200 may include: a control module 110, a radio frequency front-end module 120, a variable intermediate frequency generation module 130, an intermediate frequency conditioning module 140, and a first mixing module 150.

[0048] It is understood that, compared with the above embodiments, this embodiment adds a first mixing module 150. The input terminal of the first mixing module 150 is connected to the radio frequency front-end module 120, the output terminal of the first mixing module 150 is connected to the variable intermediate frequency generation module 130, and the first mixing module 150 is also connected to the control module 110.

[0049] The control module is also used to generate a control level based on the frequency of the radio frequency signal. The control level is used to control the opening and closing of the first mixing module. It can be understood that when the radio frequency signal is a low-frequency signal, the control level controls the first mixing module to turn on. The first mixing module is used to receive the control level and, when the radio frequency signal is a low-frequency signal, mix the low-frequency signal with a preset first local oscillator signal to generate a first intermediate frequency signal.

[0050] It should be noted that the variable intermediate frequency generation module is also used to mix the first intermediate frequency signal with the second local oscillator signal to generate a variable intermediate frequency signal when the radio frequency signal is a low-frequency signal.

[0051] In this embodiment, please refer to Figure 8 , Figure 8A structural block diagram of a first mixer module 150 is shown. The first mixer module 150 may include: a first mixer, a fourth amplifier, a fourth filter, a fifth filter, a sixth filter, a first switch (not shown in the figure), and a second switch (not shown in the figure).

[0052] The first mixer's input is connected to the output of the RF front-end module via a first switch. It receives the first local oscillator signal and, when the RF signal is low-frequency, mixes it with a preset first local oscillator signal to generate an initial first intermediate frequency (IF) signal. A fourth filter is connected to the first mixer to filter out spurious signals from the initial IF signal. A fourth amplifier is connected to the fourth filter to perform gain compensation on the filtered initial IF signal. A fifth filter is connected to the fourth amplifier to filter the gain-compensated initial IF signal to obtain the first IF signal. One end of the second switch is connected to the fifth filter, and the other end is connected to the output of the first mixer module. The control level controls the opening and closing of the first and second switches. The input of the sixth filter is connected to the output of the RF front-end module to filter the RF signal when it is not a low-frequency signal.

[0053] It is understood that by adding a first mixing module 150, the low-frequency signal can be up-converted to an intermediate frequency first, thereby avoiding false responses of the image frequency to the first intermediate frequency and improving the signal quality of the variable intermediate frequency signal.

[0054] For example, the MCU control circuit in the control module 110 can be used to output a control level, which is used to enable or bypass the first mixer module 150.

[0055] Specifically, the control level is used to control the opening and closing of the first switch and the second switch.

[0056] In the specific implementation process, the control module 110 can set the working state of the first mixer module 150 according to the pre-defined intermediate frequency configuration strategy.

[0057] When the input RF signal frequency is in the low-frequency band (RF≤3GHz), the control module 110 outputs a control level to enable the first mixer module 150 and configures the first local oscillator frequency LO1. This first converts the RF signal to a higher first intermediate frequency signal, and then, via a variable intermediate frequency generation module, converts it a second time to a lower variable intermediate frequency signal. This effectively suppresses image interference while reducing the requirements on the sampling rate of the back-end ADC.

[0058] When the input signal is in the high-frequency band (RF>3GHz), the control module 110 outputs a control level to control the RF signal to bypass the first mixer module and directly enter the variable intermediate frequency generation module for single-stage frequency conversion. At the same time, the control module 110 will synchronously adjust the frequency of the second local oscillator signal and the bandwidth of the adjustable filter in the intermediate frequency conditioning module according to the frequency band (narrowband or wideband) of the RF signal and the target instantaneous bandwidth preset by the implementer (for example, a 10MHz narrowband signal corresponds to a 10~50MHz filter bandwidth, and a 1GHz wideband signal corresponds to a 500MHz~1GHz filter bandwidth), thereby realizing flexible configuration of the receiving frequency band and bandwidth.

[0059] This embodiment performs simulation analysis on the nonlinear spurious emissions generated by each mixer under different input RF signals and preset target variable intermediate frequency signals. Please refer to the respective documentation. Figure 9 and Figure 10 , Figure 9 The simulation diagram of the first mixing nonlinear spurious signal when the input radio frequency signal in this embodiment is 2GHz to 3GHz; Figure 10 The simulation diagram of the second mixing nonlinear spurious signal when the input radio frequency signal in this embodiment is 2GHz to 3GHz.

[0060] It is understood that this embodiment can adjust the parameters of each device in the local oscillator spurious suppression circuit based on simulation results in order to effectively suppress spurious components.

[0061] It should be noted that this embodiment has developed a matching calibration algorithm for the local oscillator spurious suppression circuit. The system can monitor the output variable intermediate frequency signal in real time, and the control module 110 runs the algorithm to dynamically adjust the phase shifter control voltage and attenuator control voltage in the local oscillator spurious suppression circuit, thereby achieving adaptive cancellation of spurious components. This embodiment also designs a closed-loop control circuit, which can adjust the gain of the fourth amplifier in the intermediate frequency conditioning module 140 according to the power of the real-time monitored variable intermediate frequency signal to ensure the stability of the output variable intermediate frequency signal.

[0062] Please see Figure 11 , Figure 11 This is the second structural block diagram of the variable intermediate frequency broadband receiving system provided in the embodiments of this application. It can be understood that... Figure 11 for Figure 1 In a preferred embodiment, the variable intermediate frequency broadband receiving system 300 may include: a control module 110, a radio frequency front-end module 120, a variable intermediate frequency generation module 130, an intermediate frequency conditioning module 140, a first mixing module 160, and a second mixing module 170.

[0063] It should be noted that the structure of the first mixing module 160 in this embodiment is similar to... Figure 7The structure of the first mixing module 150 in the corresponding variable intermediate frequency broadband receiving system 200 is different. For easy distinction, the first mixing module is labeled as 160 in this embodiment.

[0064] It is understandable that this embodiment is different from... Figure 1 In a corresponding embodiment, a first mixer module 160 and a second mixer module 170 are added. The input terminal of the first mixer module 160 is connected to the RF front-end module 120, the output terminal of the first mixer module 160 is connected to the variable intermediate frequency generation module 130, and the first mixer module 160 is also connected to the control module 110. The input terminal of the second mixer module 170 is connected to the intermediate frequency conditioning module 140, and the second mixer module 170 is also connected to the control module 110.

[0065] In this embodiment, please refer to Figure 12 , Figure 12 A structural block diagram of a first mixing module 160 is shown. The first mixing module 160 may include: a first mixer, a seventh filter, an eighth filter, a fifth amplifier, and a ninth filter.

[0066] The control module 110 is further used to generate a switching control signal based on the frequency band of the radio frequency signal, and to determine a target filter from the seventh and eighth filters based on the switching control signal; the first mixer is connected to the radio frequency front-end module and is used to mix the radio frequency signal with a preset first local oscillator signal LO1 to generate an adjusted first intermediate frequency signal; the seventh and eighth filters are both connected to the first mixer and can filter the adjusted first intermediate frequency signal based on the selected target filter; the fifth amplifier is connected to the output of the seventh and eighth filters and can be used to perform gain compensation on the filtered adjusted first intermediate frequency signal to improve the signal-to-noise ratio; the eleventh filter is connected to the sixth amplifier and can be used to perform bandpass filtering on the gain-compensated adjusted first intermediate frequency signal to further suppress out-of-band noise and spurious signals, and output the final first intermediate frequency signal to the variable intermediate frequency generation module.

[0067] In addition, the output of the first mixing module 160 is connected to the variable intermediate frequency generation module 130, which is also used to mix the first intermediate frequency signal with the second local oscillator signal to generate a variable intermediate frequency signal.

[0068] In this embodiment, please refer to Figure 13 , Figure 13 A structural block diagram of a second mixer module 170 is shown. The second mixer module 170 may include: a tenth filter, a third mixer, an eleventh filter, a sixth amplifier, and a twelfth filter.

[0069] It should be noted that the control module is also connected to the third mixing module, and the control module is also used to generate a third local oscillator signal LO3; the input end of the second mixing module 170 is connected to the intermediate frequency conditioning module 140, and is used to mix the target intermediate frequency signal output by the intermediate frequency conditioning module 140 with the target signal preset by the implementer when the frequency difference between the two is greater than a preset threshold, and generate and output a final intermediate frequency signal. It can be understood that the target signal preset by the implementer is the final intermediate frequency signal that the implementer wants to obtain through the system of this embodiment, and the preset threshold can be set by the implementer according to the specific implementation scenario.

[0070] Please continue to refer to Figure 13 , the third mixer is connected to the tenth filter. The third mixer can be used to receive the target intermediate frequency signal and the third local oscillator signal LO3, and perform a third down-conversion mixing to reduce the signal frequency to the ultra-low intermediate frequency band; the eleventh filter is connected to the third mixer, the sixth amplifier is connected to the eleventh amplifier, and the twelfth filter is connected to the sixth amplifier. The tenth filter, the eleventh filter, and the twelfth amplifier can be used to stage-filter the spurious components and out-of-band noise generated during the mixing process, and the sixth amplifier can be used to perform a fixed-gain amplification on the third intermediate frequency signal after the third frequency conversion.

[0071] It should be noted that the MCU control circuit in the control module 110 is also used to output a switch control signal, and the switch control signal is used to enable or bypass-switch the first mixing module 160 and the second mixing module 170.

[0072] In a specific implementation process, the control module 110 manages the entire receiving link according to a pre-developed intermediate frequency configuration strategy.

[0073] Specifically, when the input radio frequency signal is in the low frequency band (RF ≤ 3 GHz), the control module 110 enables the first mixing module 160 and configures the first local oscillator frequency LO1 to up-convert the radio frequency signal RF to a higher first intermediate frequency IF1 to avoid image interference; then, through the variable intermediate frequency generation module 130, a second frequency conversion is performed to set the final variable intermediate frequency signal IF2 at a lower frequency to reduce the ADC sampling rate requirement.

[0074] When the input radio frequency signal is in the middle frequency band (3 GHz < RF ≤ 6 GHz), the control module 110 controls the radio frequency signal RF to pass through the first mixing module 160 and the variable intermediate frequency generation module 130 to convert the radio frequency signal RF to a variable intermediate frequency signal IF2 with a medium frequency to balance between image rejection and ADC sampling rate requirements.

[0075] When the input signal is in the high-frequency band (RF>6GHz), the control module 110 controls the RF signal to pass through the first mixer module 160 and the variable intermediate frequency generation module 130, and then further activates the second mixer module 170. The second mixer module 170 uses the third local oscillator signal LO3 to perform a third down-conversion, reducing the third intermediate frequency signal to an ultra-low fixed frequency band (such as 200~500MHz), thereby relieving the back-end processing pressure.

[0076] This embodiment performs simulation analysis on the nonlinear spurious emissions generated by each mixer under different input RF signals and preset target variable intermediate frequency signals. Please refer to the respective documentation. Figure 14 , Figure 14 The simulation diagram of the first mixing nonlinear spurious signal when the input radio frequency signal in this embodiment is 3GHz to 4GHz.

[0077] It is understood that, based on simulation results, the parameters of each device in the local oscillator spurious suppression circuit can also be adjusted in this embodiment to effectively suppress spurious components.

[0078] Figure 15 A flowchart of a variable intermediate frequency wideband receiving method provided in an embodiment of this application is shown below. Figure 15 As shown, the method may include: S21. Receive radio frequency signals within a preset frequency band; S22, Generate the second local oscillator signal and the bandwidth control signal of the adjustable filter based on the target instantaneous bandwidth; S23. Mix the radio frequency signal with the second local oscillator signal to generate a variable intermediate frequency signal; S24. Use an adjustable filter to filter the variable intermediate frequency signal to obtain the target intermediate frequency signal.

[0079] It should be noted that each step in the variable intermediate frequency broadband receiving method in this embodiment corresponds one-to-one with each module in the variable intermediate frequency broadband receiving system in the aforementioned embodiment. Therefore, the specific implementation of this embodiment can refer to the implementation of the aforementioned variable intermediate frequency broadband receiving system, and will not be repeated here.

[0080] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A variable intermediate frequency broadband receiving system, characterized in that, include: Radio frequency front-end module, variable intermediate frequency generation module, intermediate frequency conditioning module, and control module; The radio frequency front-end module is used to receive radio frequency signals within a preset frequency band. The control module is connected to the RF front-end module, the variable intermediate frequency generation module and the intermediate frequency conditioning module respectively, and is used to generate a second local oscillator signal and set the bandwidth control signal of the adjustable filter in the intermediate frequency conditioning module based on the target instantaneous bandwidth. The variable intermediate frequency generation module is connected to the radio frequency front-end module and is used to mix the radio frequency signal with the second local oscillator signal to generate a variable intermediate frequency signal. The intermediate frequency conditioning module is connected to the variable intermediate frequency generation module and includes an adjustable filter. The intermediate frequency conditioning module uses the adjustable filter to filter the variable intermediate frequency signal to obtain the target intermediate frequency signal.

2. The system according to claim 1, characterized in that, The variable intermediate frequency generation module includes: a second mixer, a local oscillator spurious suppression circuit, and an adjustable filter circuit; The second mixer is used to receive the second local oscillator signal and mix the radio frequency signal with the second local oscillator signal to generate an initial variable intermediate frequency signal; The local oscillator spurious suppression circuit is connected to the second mixer and is used to suppress the local oscillator leakage spurious in the initial variable intermediate frequency signal to generate a purified variable intermediate frequency signal. The adjustable filter circuit is connected to the local oscillator spurious suppression circuit and is used to perform bandpass filtering on the purified variable intermediate frequency signal to output a variable intermediate frequency signal.

3. The system according to claim 1, characterized in that, The system further includes: a first mixer module; The control module is also connected to the first mixer module and is used to generate a first local oscillator signal and to generate a control level based on the frequency of the radio frequency signal. The control level is used to control the opening and closing of the first mixer module. The first mixing module is used to receive the control level and, when the radio frequency signal is a low-frequency signal, mix the radio frequency signal with the first local oscillator signal to generate a first intermediate frequency signal; The output of the first mixing module is connected to the variable intermediate frequency generation module. The variable intermediate frequency generation module is further used to mix the first intermediate frequency signal with the second local oscillator signal to generate a variable intermediate frequency signal when the radio frequency signal is a low frequency signal.

4. The system according to claim 3, characterized in that, The first mixer module includes: The system comprises a first mixer, a fourth amplifier, a fourth filter, a fifth filter, a sixth filter, a first switch, and a second switch. The input terminal of the first mixer is connected to the output terminal of the radio frequency front-end module through the first switch, and is used to receive the first local oscillator signal. When the radio frequency signal is a low-frequency signal, the radio frequency signal is mixed with the preset first local oscillator signal to generate an initial first intermediate frequency signal. The fourth filter is connected to the first mixer and is used to filter out spurious signals in the initial first intermediate frequency signal; The fourth amplifier is connected to the fourth filter and is used to perform gain compensation on the filtered initial first intermediate frequency signal. The fifth filter is connected to the fourth amplifier and is used to filter the initial first intermediate frequency signal after gain compensation to obtain the first intermediate frequency signal. One end of the second switch is connected to the fifth filter, and the other end is connected to the output of the first mixer module. The control level is used to control the opening and closing of the first switch and the second switch. The input terminal of the sixth filter is connected to the output terminal of the RF front-end module, and is used to filter the RF signal when the RF signal is not a low-frequency signal.

5. The system according to claim 1, characterized in that, The system further includes: a first mixing module, which includes a first mixer, a seventh filter, and an eighth filter; The control module is also connected to the first mixer module and is used to generate a first local oscillator signal, generate a switch control signal based on the frequency band of the radio frequency signal, and determine a target filter from the seventh filter and the eighth filter based on the switch control signal. The input terminal of the first mixer is connected to the output terminal of the radio frequency front-end module, and is used to mix the radio frequency signal with the first local oscillator signal to generate an adjusted first intermediate frequency signal. Both the seventh filter and the eighth filter are connected to the first mixer and are used to filter the adjusted first intermediate frequency signal based on the target filter to obtain the first intermediate frequency signal. The output of the first mixing module is connected to the variable intermediate frequency generation module, and the variable intermediate frequency generation module is also used to mix the first intermediate frequency signal with the second local oscillator signal to generate a variable intermediate frequency signal.

6. The system according to claim 5, characterized in that, The system further includes: a second mixer module; The control module is also connected to the second mixer module for generating a third local oscillator signal; The input terminal of the second mixing module is connected to the intermediate frequency conditioning module, and is used to mix the target intermediate frequency signal with the third local oscillator signal to generate and output the final intermediate frequency signal when the frequency difference between the target intermediate frequency signal and the preset target signal is greater than a preset threshold.

7. The system according to claim 1, characterized in that, The radio frequency front-end module includes a limiter, an adjustable amplifier, a first filter, a first attenuator, and a second filter; The limiter is used to clamp the power of instantaneous high-power signals in the radio frequency signal; The adjustable amplifier is connected to the limiter and is used to amplify the radio frequency signal when the power of the radio frequency signal is less than a preset power threshold. The first filter is connected to the adjustable amplifier and is used to filter the amplified radio frequency signal. The first attenuator is connected to the limiter and is used to perform fixed attenuation of the radio frequency signal when the power of the radio frequency signal is greater than or equal to a preset power threshold. The second filter is connected to the first attenuator and is used to filter the attenuated radio frequency signal.

8. The system according to claim 6, characterized in that, The second mixing module includes: a third mixer; The third mixer is used to mix the target intermediate frequency signal with the third local oscillator signal when the frequency difference between the target intermediate frequency signal and the preset target signal is greater than a preset threshold.

9. The system according to claim 5, characterized in that, The first mixer module further includes: a fifth amplifier and a ninth filter; The input terminal of the fifth amplifier is connected to the output terminals of the seventh and eighth filters, and is used to perform gain compensation on the filtered adjusted first intermediate frequency signal. The ninth filter is connected to the fifth amplifier and is used to filter the adjusted first intermediate frequency signal after gain compensation in order to suppress out-of-band noise.

10. A variable intermediate frequency broadband receiving method, characterized in that, Applied to the system according to any one of claims 1-9, the method comprises: Receives radio frequency signals within a preset frequency band; Generate a second local oscillator signal and set the bandwidth control signal of the adjustable filter in the intermediate frequency conditioning module based on the target instantaneous bandwidth; The radio frequency signal is mixed with the second local oscillator signal to generate a variable intermediate frequency signal; The variable intermediate frequency signal is filtered using the adjustable filter to obtain the target intermediate frequency signal.

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