A low-noise harmonic suppression RF system for filter band control

Abstract

The present invention discloses a low-noise harmonic suppression radio frequency system for filter band control, comprising a Chebyshev low-pass frequency hopping filter, a weight element parameter control module, a harmonic suppression module, and a low-noise amplifier; wherein the Chebyshev low-pass frequency hopping filter comprises a plurality of weight elements; an external radio frequency signal is used as the input of the Chebyshev low-pass frequency hopping filter, and the output end of the external radio frequency signal is connected to the input end of the harmonic suppression module; the weight element parameter control module is connected to the weight elements of the Chebyshev low-pass frequency hopping filter via a multi-way selection switch; the input end of the harmonic suppression module is connected to the output end of the Chebyshev low-pass frequency hopping filter; the low-noise amplifier is connected to the output end of the harmonic suppression module; and the input end of the low-noise amplifier is connected to the output end of the harmonic suppression module. Through the coordinated operation of the above modules, the radio frequency signal can be efficiently processed, and the goals of frequency band control, harmonic suppression, and noise suppression can be achieved.

Description

Technical Field

[0001] The present invention relates to the field of radio frequency technology, and in particular to a low-noise harmonic suppression radio frequency system for filter band control. Background Art

[0002] With the rapid development of radio frequency communication technology, harmonic suppression and low-noise design have become particularly important in filter band control systems. While existing harmonic suppression technologies can meet basic requirements to a certain extent, they still have many shortcomings in multi-band, wide dynamic range applications. For example, existing harmonic suppression solutions often rely on complex filter banks and band control circuits, resulting in larger system size and increased costs, while also making it difficult to achieve efficient harmonic suppression and low-noise performance.

[0003] A search revealed a harmonic suppression method and corresponding low-noise amplifier and communication terminal with publication number CN106160673B, published on March 30, 2021. This technology improves the design flexibility of the signal amplification circuit by providing an isolation unit between the harmonic suppression unit and the output matching network / input matching network of the low-noise amplifier. However, this solution primarily targets harmonic suppression in a single frequency band and does not address the band control issues of multi-band filters. Furthermore, the design of the isolation unit increases circuit complexity, making it difficult to achieve efficient harmonic suppression and low-noise performance in broadband applications.

[0004] A search revealed a broadband harmonic suppression amplifier with publication number CN114172464B, published on May 24, 2022. This technology utilizes broadband current multiplexing and a common-source amplifier network, coupled with a gate-source RLC parallel negative feedback circuit, to achieve wideband, high gain, and low power consumption. While this solution offers some improvements in broadband harmonic suppression, the design of its harmonic suppression equalization matching network is complex and lacks optimization for filter band control, making it difficult to achieve efficient harmonic suppression and low noise performance in multi-band applications.

[0005] The aforementioned issues demonstrate that existing harmonic suppression technologies suffer from complex designs and insufficient performance in multi-band, wide-dynamic-range filter band control systems. Therefore, the present invention provides a low-noise harmonic suppression RF system for filter band control to overcome these shortcomings and provide a new, more efficient, flexible, and adaptable solution for multi-band applications. Summary of the Invention

[0006] The present invention aims to provide a low-noise harmonic suppression radio frequency system for filter band control to solve the above-mentioned problems.

[0007] The present invention is achieved through the following technical solutions:

[0008] A low-noise harmonic suppression radio frequency system for filter band control, comprising a Chebyshev low-pass frequency hopping filter, a weight element parameter control module, a harmonic suppression module and a low-noise amplifier;

[0009] The Chebyshev low-pass frequency hopping filter includes a plurality of weighted elements, each of which has an adjustable capacitance and inductance. The capacitance and inductance of the weighted elements are dynamically adjusted by a weighted element parameter control module to achieve frequency response switching in multiple frequency bands.

[0010] The input end of the Chebyshev low-pass frequency hopping filter is connected to the input end of the external radio frequency signal, and the output end thereof is connected to the input end of the harmonic suppression module;

[0011] The weight element parameter control module is connected to the weight element of the Chebyshev low-pass frequency hopping filter through a multi-way selection switch, and the multi-way selection switch selects different weight element combinations according to a preset frequency switching instruction;

[0012] The harmonic suppression module includes multiple harmonic suppression units. Each harmonic suppression unit suppresses harmonics in a specific frequency band through a low-pass filter and a notch filter. The harmonic suppression module is connected to the output end of the Chebyshev low-pass frequency hopping filter to further suppress harmonics on the signal output by the filter.

[0013] The low-noise amplifier is connected to the output end of the harmonic suppression module and is used to perform low-noise amplification on the signal that has undergone harmonic suppression processing. A negative feedback circuit is provided inside the low-noise amplifier to compensate for nonlinear distortion during the amplification process.

[0014] The input end of the low noise amplifier is connected to the output end of the harmonic suppression module, and the output end of the low noise amplifier is connected to the output end of a low noise harmonic suppression radio frequency system for filter band control.

[0015] Preferably, the weight element parameter control module includes a central processing unit, a data storage device, a signal transceiver and a power management module;

[0016] The central processing unit is connected to the data storage device via a data bus and is used to store and process frequency switching instructions and generate corresponding weight element combination selection signals according to the instructions; the signal transceiver is connected to the central processing unit and is used to receive and send instruction signals; the power management module is connected to the central processing unit and is used to manage and distribute the power provided by the power module;

[0017] The weight element parameter control module is connected to the weight elements of the Chebyshev low-pass frequency hopping filter via a multi-way selection switch. The multi-way selection switch selects different weight element combinations according to preset frequency switching instructions to adjust the frequency response of the filter; the frequency response of the weight element combination is periodically calibrated to ensure the frequency response accuracy of the filter.

[0018] Preferably, the input end of the harmonic suppression module is connected to the output end of the Chebyshev low-pass frequency hopping filter, and the output end thereof is connected to the input end of the low-noise amplifier. The working method of the harmonic suppression module is:

[0019] S1: The harmonic suppression module receives the output signal from the Chebyshev low-pass frequency hopping filter and divides the signal into multiple frequency bands;

[0020] S2: Perform harmonic analysis on the signal of each frequency band to determine the harmonic frequency band that needs to be suppressed; perform low-pass filtering on the main frequency band signal through a low-pass filter to remove high-frequency noise;

[0021] S3: Use the notch filter to notch the harmonics in a specific frequency band and suppress the harmonic signals;

[0022] S4: Merge the processed signals of each frequency band and output a signal that has undergone harmonic suppression processing.

[0023] Preferably, the notch filter is designed by the following steps:

[0024] S1: Determine the center frequency and bandwidth of the notch filter based on the harmonic frequency range of the target frequency band;

[0025] S2: Design the transfer function of the notch filter so that it has maximum attenuation at the center frequency;

[0026] S3: Optimize the frequency response characteristics of the notch filter by adjusting the capacitance and inductance values;

[0027] S4: Combine the notch filter with the low-pass filter to form a multi-stage harmonic suppression network.

[0028] Preferably, the center frequency of the notch filter is determined by the following formula according to the harmonic frequency range of the target frequency band: and bandwidth :

[0029] ;

[0030] ;

[0031] in is the harmonic frequency, is the center frequency of the target frequency band.

[0032] Preferably, the transfer function H(s) of the notch filter is designed so that it is The maximum attenuation is at: ;

[0033] Where Q is the quality factor, which represents the sharpness of the notch filter, s is the complex frequency variable in the Laplace transform, and Δf is the bandwidth of the notch filter.

[0034] Preferably, the capacitance value of the notch filter is adjusted by the following formula: and inductance value , optimize its frequency response characteristics:

[0035] ;

[0036] ;in, is the resistance value.

[0037] Preferably, the low-noise amplifier receives the output signal from the harmonic suppression module and inputs the signal into the amplification circuit; the nonlinear distortion in the amplification process is compensated by the negative feedback circuit to ensure the linearity of the amplified signal; the amplified signal is subjected to noise suppression processing to remove the noise introduced in the amplification process, and the low-noise amplified signal is output;

[0038] The negative feedback circuit design method of a low-noise amplifier includes the following steps: determining the feedback coefficient of the negative feedback circuit according to the gain requirements and nonlinear distortion characteristics of the amplifier; designing the transfer function of the negative feedback circuit so that it can effectively compensate for the nonlinear distortion during the amplification process; optimizing its frequency response characteristics by adjusting the resistance and capacitance values ​​of the negative feedback circuit; and combining the negative feedback circuit with the amplifier circuit to form a low-noise amplifier network.

[0039] Preferably, according to the gain requirement and nonlinear distortion characteristics of the amplifier, the feedback coefficient of the negative feedback circuit is determined by the following formula: ;in, is the feedback resistor, is the input resistance.

[0040] Preferably, the transfer function of the negative feedback circuit is designed to be , which is expressed as follows: ;in, is the open-loop gain of the amplifier.

[0041] Preferably, the resistance value of the negative feedback circuit is adjusted by the following formula: and capacitance value : ;

[0042] in, is the angular frequency.

[0043] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0044] 1. Through the coordinated work of the Chebyshev low-pass frequency hopping filter, the weight element parameter control module, the harmonic suppression module and the low-noise amplifier, the RF signal can be processed efficiently and the goals of frequency band control, harmonic suppression and noise suppression can be achieved.

[0045] 2. By controlling the parameters of the weighted components through the central processor and combining them with the flexible switching of the multi-way selector switch, the system can accurately adjust the filter's operating frequency response in real time to meet the requirements of different application scenarios. This flexibility enables the RF system to operate stably across a wide frequency band, avoiding the performance loss caused by fixed frequency band restrictions.

[0046] 3. Through precise frequency band division and harmonic suppression, the system can effectively remove interference from high-frequency noise and unnecessary harmonic components, maintaining signal purity. This is particularly important for demanding RF applications and can significantly improve the system's signal-to-noise ratio and overall performance.

[0047] 4. The notch filter design ensures deep attenuation of harmonic interference at specific frequencies without significantly affecting the main signal frequency. By adjusting the capacitance and inductance values, the frequency response can be optimized, ensuring that signal distortion does not occur during signal transmission, and the main signal remains clear and stable.

[0048] 5. By designing the transfer function, maximum attenuation can be achieved at the center frequency, ensuring that the system effectively suppresses harmonics within this frequency range. In this way, the main signal of the RF system can be protected without being interfered with by higher harmonics. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0050] Figure 1 It is a structural block diagram of the system of the present invention. DETAILED DESCRIPTION

[0051] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the examples and accompanying drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention. It should be noted that the present invention is already in the actual development and use stage.

[0052] See Figure 1An embodiment of the present invention provides a low-noise harmonic suppression radio frequency system for filter band control, comprising a Chebyshev low-pass frequency hopping filter, a weight element parameter control module, a harmonic suppression module and a low-noise amplifier; wherein the Chebyshev low-pass frequency hopping filter comprises a plurality of weight elements, each of which has an adjustable capacitance value and inductance value, and the capacitance value and inductance value of the weight element are dynamically adjusted by the weight element parameter control module to achieve frequency response switching of multiple bands; the input end of the Chebyshev low-pass frequency hopping filter is connected to the input end of the external radio frequency signal, and the output end thereof is connected to the input end of the harmonic suppression module; the weight element parameter control module is connected to the weight elements of the Chebyshev low-pass frequency hopping filter through a multi-way selection switch, and the multi-way selection switch is configured to adjust the capacitance value and inductance value of the weight element according to the preset capacitance value and inductance value. The frequency switching instruction set selects different weight element combinations; the harmonic suppression module includes multiple harmonic suppression units, each harmonic suppression unit suppresses harmonics in a specific frequency band through a low-pass filter and a notch filter, and the harmonic suppression module is connected to the output end of the Chebyshev low-pass frequency hopping filter for further harmonic suppression processing of the signal output by the filter; the low-noise amplifier is connected to the output end of the harmonic suppression module for low-noise amplification of the signal after harmonic suppression processing, and a negative feedback circuit is provided inside the low-noise amplifier for compensating for nonlinear distortion during the amplification process; the input end of the low-noise amplifier is connected to the output end of the harmonic suppression module, and the output end is connected to the output end of a low-noise harmonic suppression radio frequency system for filter band control.

[0053] In one possible implementation, a Chebyshev low-pass frequency-hopping filter, serving as the core of the system, can dynamically switch filtering characteristics based on the frequency band requirements of the input signal. It is composed of multiple weighting elements. The capacitance and inductance values ​​of each weighting element can be adjusted via a weighting element parameter control module. Specifically, the parameter control module uses a multi-way selector switch to control different capacitor and inductor combinations, thereby varying the filter's cutoff frequency, allowing the filter to switch between multiple frequency bands as needed. This dynamic adjustment ensures that the signal's frequency response meets the needs of different applications, avoiding performance losses caused by fixed frequency bands.

[0054] Furthermore, the weight element parameter control module, through its connection to the Chebyshev low-pass frequency hopping filter, precisely controls the capacitance and inductance values ​​of each weight element. Specifically, the control module uses a multi-way selector switch to select different combinations of capacitance and inductance values ​​to achieve the preset frequency response. Frequency switching commands for each frequency band result in different capacitance and inductance combinations, thereby adjusting the filter's operating state. This switching effectively supports complex RF applications, ensuring that signals are appropriately filtered across different frequency bands.

[0055] Furthermore, after the Chebyshev filter outputs the signal, the harmonic suppression module further improves signal quality. This module comprises multiple harmonic suppression units, each of which uses a low-pass filter and a notch filter to suppress harmonics within a specific frequency band. The low-pass filter eliminates high-frequency noise, while the notch filter selectively attenuates specific harmonic frequencies. In this way, the harmonic suppression module effectively reduces nonlinear distortion and unnecessary high-order harmonics in the system's output signal, thereby improving the overall performance of the RF system.

[0056] Finally, the low-noise amplifier (LNA) performs low-noise amplification on the harmonically suppressed signal to enhance signal strength. A negative feedback circuit is designed within the LNA to compensate for nonlinear distortion during the amplification process and ensure output signal quality. The use of a LNA minimizes noise gain during signal processing, providing a more stable and clear signal output. This amplification process is particularly important in RF systems, as it not only increases signal power but also ensures that noise levels are suppressed during the gain process.

[0057] Through the above design, this low-noise harmonic suppression RF system provides flexible frequency switching capabilities across multiple frequency bands while effectively suppressing higher harmonics and noise. Dynamic adjustment of the weight element parameter control module enables the system to automatically optimize frequency response based on different application scenarios, ensuring adaptability across a wide frequency band. The complementary design of the harmonic suppression module and the low-noise amplifier ensures improved signal quality, reduces nonlinear distortion and noise, and ultimately outputs high-quality RF signals. Furthermore, the negative feedback circuit further reduces distortion during amplification, ensuring the system's linear response.

[0058] In an embodiment of the present invention, a weight element parameter control module includes a central processing unit, a data storage device, a signal transceiver and a power management module; the central processing unit is connected to the data storage device through a data bus, and is used to store and process frequency switching instructions, and generate corresponding weight element combination selection signals according to the instructions; the signal transceiver is connected to the central processing unit, and is used to receive and send instruction signals; the power management module is connected to the central processing unit, and is used to manage and distribute the power provided by the power module; the weight element parameter control module is connected to the weight elements of the Chebyshev low-pass frequency hopping filter through a multi-way selection switch, and the multi-way selection switch selects different weight element combinations according to preset frequency switching instructions to achieve frequency response adjustment of the filter; the frequency response of the weight element combination is periodically calibrated to ensure the frequency response accuracy of the filter.

[0059] In one possible implementation, the design and functionality of the weight element parameter control module ensures dynamic adjustment and high-precision calibration of the Chebyshev low-pass frequency hopping filter's frequency response through precise signal control and power management. Specifically, the weight element parameter control module includes a central processing unit (CPU), data storage, signal transceiver, and power management module. These components are interconnected via a data bus and signal interface, working together to ensure the system can flexibly and efficiently adjust the filter's operating frequency based on different application scenarios or requirements.

[0060] Specifically, the central processing unit (CPU) receives and processes external commands. Connected to a data memory via a data bus, the CPU retrieves frequency switching instructions and filter operating parameters from the memory. These instructions and parameters include the capacitor and inductor value combinations required for frequency band switching, as well as other configuration data.

[0061] Furthermore, the signal transceiver serves as an input / output interface, enabling communication with external devices or systems. It transmits frequency switching instructions generated by the CPU to external devices and simultaneously receives feedback to ensure the instructions are correctly executed. The signal transceiver acts as a bridge for command transmission throughout the system.

[0062] Furthermore, the power management module is responsible for monitoring and allocating power within the system, ensuring stable operation of all components, particularly the CPU, signal transceivers, and multiplexers. It allocates power based on the CPU's needs, ensuring a stable and efficient power supply throughout the system.

[0063] Furthermore, during filter operation, the multi-way selector switches, based on the selection signal generated by the central processor, select different weighted component combinations to adjust the frequency response of the Chebyshev low-pass frequency-hopping filter. By dynamically adjusting these component combinations, the system can switch frequencies, adapting the filter's operating frequency response to different application requirements.

[0064] To ensure the Chebyshev filter's frequency response remains highly accurate, the system periodically calibrates the frequency response of the weighting element combination. This calibration process uses real-time feedback from the central processor and sensors to adjust the weighting element parameters, ensuring that the filter's accuracy during frequency switching is unaffected by the external environment or component aging.

[0065] In an embodiment of the present invention, the input end of the harmonic suppression module is connected to the output end of the Chebyshev low-pass frequency hopping filter, and the output end is connected to the input end of the low-noise amplifier. The working method of the harmonic suppression module is as follows: S1: the harmonic suppression module receives the output signal from the Chebyshev low-pass frequency hopping filter and divides the signal into multiple frequency bands; S2: harmonic analysis is performed on the signal of each frequency band to determine the harmonic frequency band that needs to be suppressed; the main frequency band signal is low-pass filtered by a low-pass filter to remove high-frequency noise; S3: the harmonics of a specific frequency band are notched by a notch filter to suppress the harmonic signal; S4: the processed signals of each frequency band are merged and the signal after harmonic suppression is output.

[0066] In one possible implementation, the input of the harmonic suppression module is connected to the output of a Chebyshev low-pass frequency-hopping filter. The Chebyshev low-pass frequency-hopping filter extracts the main frequency band signal from the input signal and removes some unnecessary frequency components. The harmonic suppression module receives this output signal and provides the filtered frequency components for subsequent harmonic analysis and processing.

[0067] Furthermore, the harmonic suppression module first divides the received signal into multiple frequency bands. The key to this process is precise signal segmentation, allowing each band to be processed independently. The segmented signal makes subsequent harmonic analysis easier, preventing interference between different frequency bands.

[0068] Furthermore, each segmented frequency band undergoes harmonic analysis to identify which frequency bands contain harmonic interference. For the main frequency band signal, the system uses a low-pass filter to remove high-frequency noise and maintain a pure signal spectrum. During this process, the low-pass filter primarily removes noise components exceeding a certain frequency threshold, retaining the useful signal frequencies.

[0069] For harmonic frequency bands that require suppression, the harmonic suppression module uses a notch filter to perform specialized notch processing. Notch filters precisely remove signals within specific frequency ranges, typically spurious frequencies generated by harmonic effects. By precisely targeting these frequencies, notch filters effectively suppress these harmonic components, preventing them from affecting other parts of the system.

[0070] Finally, the processed signals from each frequency band are combined to form an overall output signal that has undergone harmonic suppression. This signal is then fed into the input of a low-noise amplifier, ensuring that signal quality is maintained throughout the entire RF system.

[0071] In an embodiment of the present invention, the notch filter is designed through the following steps: S1: determining the center frequency and bandwidth of the notch filter based on the harmonic frequency range of the target frequency band; S2: designing the transfer function of the notch filter so that it has maximum attenuation at the center frequency; S3: optimizing the frequency response characteristics of the notch filter by adjusting the capacitance and inductance values ​​of the notch filter; S4: combining the notch filter with a low-pass filter to form a multi-stage harmonic suppression network.

[0072] In one possible implementation, notch filter design begins by determining the harmonic frequency range within the target frequency band. Harmonic interference is typically caused by nonlinear effects in the input signal, with the resulting harmonics typically occurring at integer multiples of the input signal's frequency. Therefore, designers first need to calculate the potential harmonic frequencies based on the system's main input signal frequency band. Based on this information, designers can select an appropriate center frequency and bandwidth to effectively suppress these harmonics.

[0073] After determining the center frequency and bandwidth, designers need to design the notch filter's transfer function to ensure maximum attenuation at the specified center frequency. The goal of the transfer function is to ensure that the filter deeply attenuates harmonic frequencies while remaining transparent to signals in other frequency bands. During design, the filter's quality factor and bandwidth can be adjusted to optimize performance.

[0074] Furthermore, the core components of a notch filter are typically capacitors and inductors. Therefore, during the design process, the filter's frequency response characteristics must be optimized by adjusting the capacitor and inductor values. The specific values ​​of the inductor and capacitor determine the filter's center frequency and bandwidth. Therefore, through precise calculation and adjustment, it is possible to ensure that the filter effectively suppresses harmonics within the required frequency range while avoiding interference with the main frequency band signal.

[0075] Furthermore, after the notch filter is designed and optimized, it is combined with a low-pass filter to form a multi-stage harmonic suppression network. The low-pass filter effectively filters out high-frequency noise, while the notch filter specifically attenuates specific harmonics. This combination enables more precise signal processing. The low-pass filter is typically placed at the front end to remove high-frequency noise, while the notch filter is placed at the back end as needed to remove specific frequency harmonics.

[0076] In the embodiment of the present invention, the center frequency of the notch filter is determined by the following formula according to the harmonic frequency range of the target frequency band: and bandwidth :

[0077] ;

[0078] ;

[0079] in is the harmonic frequency, is the center frequency of the target frequency band.

[0080] In a possible implementation, first, the operating frequency band of the radio frequency system, that is, the target frequency band, is determined. Generally, in RF systems, the target frequency band is the range where the main signal frequency is located. The harmonic frequencies are caused by nonlinear effects in the system (such as power amplifiers, etc.) and are usually located at integer multiples of the target frequency band. For example, if the signal frequency in the target frequency band is , then the harmonics may appear in At equal frequencies.

[0081] According to the given formula, the center frequency and bandwidth of the notch filter can be calculated by the following steps:

[0082] Center frequency Calculated as the average of the center frequency and harmonic frequencies of the target frequency band: This calculation method means that the design of the notch filter will locate a suitable center frequency between the target frequency band and the harmonic frequency, thereby accurately suppressing harmonic interference.

[0083] bandwidth It is determined by the difference between the target frequency band and the harmonic frequency: ; This bandwidth definition ensures that the notch filter can cover the frequency range from the target frequency band to the harmonic frequency band and effectively suppress the interference of harmonic signals.

[0084] Once the center frequency and bandwidth are determined, the designer can adjust the notch filter circuit structure based on these parameters and select appropriate inductor and capacitor components to achieve the desired frequency response. Typically, the notch filter optimizes its bandwidth by adjusting its quality factor (Q value) to ensure that the signal between the target frequency band and the harmonic frequency band can be effectively suppressed.

[0085] In practical applications, notch filters often work in conjunction with other filters (such as low-pass filters) to form a multi-stage filtering network. Low-pass filters are typically used to remove high-frequency noise above the target frequency band, while notch filters are specifically designed to deeply attenuate harmonics. By working in tandem with these multi-stage filters, the system can effectively remove harmonic interference without distorting the target signal.

[0086] In the embodiment of the present invention, the transfer function H(s) of the notch filter is designed so that it can be used at the center frequency by the following formula: The maximum attenuation is at: ;

[0087] Where Q is the quality factor, which represents the sharpness of the notch filter, s is the complex frequency variable in the Laplace transform, and Δf is the bandwidth of the notch filter.

[0088] In one possible implementation, first, based on the analysis of the target frequency band and the harmonic frequency band, the designer determines the center frequency of the notch filter. and bandwidth The center frequency is usually chosen to be a suitable point between the target signal frequency and the harmonic frequencies, while the bandwidth is determined by the distribution of the harmonic frequencies and the width of the target frequency band.

[0089] The quality factor determines the sharpness of the filter and indicates its frequency selectivity. A higher Q value means a narrower bandwidth at the center frequency, resulting in a more pronounced suppression effect. During design, the appropriate Q value should be selected based on the actual harmonic frequency characteristics and system requirements.

[0090] Once it is determined , the designer can construct the mathematical model of the filter based on the above transfer function formula. This transfer function is in the form of a second-order low-pass filter with two identical quadratic terms that represent the effect of the filter on the signal.

[0091] In analog circuit design, the transfer function It is converted into a specific combination of circuit components (such as resistors, inductors, and capacitors). By adjusting the values ​​of these components, the designer can achieve the desired frequency response so that the notch filter produces maximum attenuation at the center frequency.

[0092] By designing the transfer function, maximum attenuation can be achieved at the center frequency, ensuring that the system effectively suppresses harmonics within this frequency range. In this way, the main signal of the RF system can be protected without being interfered with by higher harmonics.

[0093] In the embodiment of the present invention, the capacitance value of the notch filter is adjusted by the following formula: and inductance value , optimize its frequency response characteristics:

[0094] ;

[0095] ;in, is the resistance value.

[0096] In one possible implementation, the center frequency is first determined based on the desired harmonic suppression frequency. , which is the frequency point near the target signal frequency. Then, calculate the appropriate capacitance value based on the selected center frequency and formula and inductance value .

[0097] Furthermore, to achieve effective harmonic suppression, the filter bandwidth must be adjusted, which can be achieved by adjusting the resistors and inductors. The narrower the bandwidth, the more selective the filter is at the center frequency, allowing for more precise suppression of target harmonics without affecting other signals. By adjusting the inductors and resistors, the desired bandwidth can be achieved.

[0098] In actual circuits, capacitors, inductors, and resistors form the core components of a notch filter. The values ​​of the capacitors and inductors determine the filter's frequency response, while the resistor affects the bandwidth and quality factor (Q). By adjusting the values ​​of these components, the filter's frequency response can be precisely controlled, achieving maximum attenuation within the target frequency band.

[0099] By adjusting the values ​​of the inductor and capacitor, the center frequency of the notch filter can be precisely controlled, ensuring the filter's suppression effect on the target harmonics. Precise control of the harmonic frequency position enables the system to effectively filter out unwanted higher harmonics without affecting the main signal.

[0100] In an embodiment of the present invention, a low-noise amplifier receives an output signal from a harmonic suppression module and inputs the signal into an amplification circuit; nonlinear distortion in the amplification process is compensated for through a negative feedback circuit to ensure the linearity of the amplified signal; noise suppression processing is performed on the amplified signal to remove noise introduced during the amplification process, and a signal subjected to low-noise amplification processing is output; a negative feedback circuit design method for a low-noise amplifier includes the following steps: determining a feedback coefficient of the negative feedback circuit based on the gain requirements and nonlinear distortion characteristics of the amplifier; designing a transfer function of the negative feedback circuit so that it can effectively compensate for the nonlinear distortion in the amplification process; optimizing its frequency response characteristics by adjusting the resistance and capacitance values ​​of the negative feedback circuit; and combining the negative feedback circuit with the amplification circuit to form a low-noise amplification network.

[0101] In this embodiment of the present invention, the feedback coefficient required for the negative feedback circuit is first determined based on the gain requirements and nonlinear distortion requirements of the low-noise amplifier. The gain requirement determines the basic gain of the amplifier, while the nonlinear distortion characteristics affect signal fidelity. Generally, excessive gain easily leads to nonlinear distortion, so a balance between gain and distortion is required during design.

[0102] The transfer function of a negative feedback circuit determines the amplitude and phase characteristics of the feedback signal. This transfer function is used to design a negative feedback network that effectively compensates for the nonlinear distortion generated in the amplifier. Negative feedback can suppress high-order harmonic components by reducing the amplifier's gain, thereby making the signal more linear.

[0103] Furthermore, the frequency response characteristics of the negative feedback circuit can be optimized by adjusting the resistance and capacitance values. The choice of resistance and capacitance values ​​directly affects the behavior of the feedback circuit at different frequencies, thereby affecting the linear amplification effect of the signal. During the design process, it is necessary to ensure that the negative feedback circuit has sufficient bandwidth within the required operating frequency band to effectively compensate for nonlinear distortion.

[0104] After the design is complete, the negative feedback circuit is combined with the amplifier circuit to form a low-noise amplifier network. In the actual circuit, the negative feedback circuit forms a closed loop by connecting the output and input of the amplifier. In this way, the feedback loop adjusts the gain and compensates for nonlinear distortion.

[0105] The design and optimization of negative feedback circuits can effectively improve the performance of low-noise amplifiers, improve the linearity of the system, reduce nonlinear distortion and noise interference, and thus improve the signal quality and stability of the entire RF system.

[0106] In the embodiment of the present invention, the feedback coefficient of the negative feedback circuit is determined by the following formula according to the gain requirement and nonlinear distortion characteristics of the amplifier: ;in, is the feedback resistor, is the input resistance.

[0107] In one possible implementation, the design process first analyzes the low-noise amplifier's gain requirements and the system's nonlinear distortion requirements. Excessive gain can easily introduce nonlinear distortion, while appropriate negative feedback can effectively reduce this distortion. By selecting an appropriate feedback factor, the system can maintain the desired gain while suppressing the generation of high-order harmonics.

[0108] Furthermore, the feedback coefficient formula allows designers to select an appropriate ratio between the feedback resistor and the input resistor. This ratio determines the amplifier's closed-loop gain and influences its frequency response and nonlinear characteristics. Specifically, the feedback resistor adjusts the gain and reduces nonlinear distortion by feeding a portion of the output signal back to the input. The input resistor, on the other hand, determines the interaction between the input signal's impedance and the feedback signal.

[0109] In practical circuits, a feedback resistor is typically connected between the amplifier's output and input, forming a closed loop. Through this connection, a portion of the amplifier's output signal is fed back to the input, thereby adjusting the gain and stabilizing the amplifier's gain. An input resistor, typically connected at the amplifier's input, works together with the feedback circuit to influence signal processing.

[0110] By selecting appropriate feedback resistors and input resistors and designing a reasonable negative feedback network, the low-noise amplifier can effectively suppress harmonic distortion, optimize gain and frequency response, and thus improve the performance and stability of the entire RF system.

[0111] In the embodiment of the present invention, the transfer function of the negative feedback circuit is designed to be , which is expressed as follows: ;in, is the open-loop gain of the amplifier.

[0112] In one possible implementation, the open-loop gain of an amplifier is the gain of the input signal without any feedback loop. When designing low-noise, harmonic-suppression RF systems, the open-loop gain is typically high. However, this can lead to undesirable frequency response due to nonlinear distortion or excessive gain, necessitating optimization through negative feedback.

[0113] Furthermore, a negative feedback circuit typically includes a feedback resistor and an input resistor. The feedback signal is fed back from the amplifier's output to its input, forming a closed loop. The feedback coefficient, which determines the amplitude of the feedback signal, is determined by both the feedback resistor and the input resistor. The output signal is fed back to the amplifier's input through the feedback resistor, while the input signal interacts with the feedback signal through the input resistor.

[0114] The introduction of negative feedback will cause the gain of the amplifier to change. Through Laplace transform, the closed-loop gain of the negative feedback system can be described by the following formula:

[0115] ;in, is the feedback coefficient, which controls the influence of the feedback signal on the input signal. There may be nonlinear characteristics, and negative feedback adjusts the gain so that the closed-loop gain is greater than the open-loop gain. More stable and linear.

[0116] The closed-loop gain has higher stability than the open-loop gain and has smaller gain fluctuation. As the feedback coefficient increases, the closed-loop gain tends to be stable, reducing the nonlinear distortion introduced by excessive gain in the system. In practice, by adjusting , the gain of the amplifier can be precisely controlled to achieve a low-noise, low-distortion RF system.

[0117] By designing an appropriate negative feedback circuit and utilizing its transfer function, harmonics can be effectively suppressed, the system linearity and frequency response can be improved, and the system stability and reliability can be enhanced, thereby optimizing the overall performance of the RF system, especially in filter band control.

[0118] In the embodiment of the present invention, the resistance value of the negative feedback circuit is adjusted by the following formula: and capacitance value : ;in, is the angular frequency.

[0119] In one possible implementation, in a radio frequency system, a negative feedback circuit is typically composed of a resistor and a capacitor. The configuration of these two components can affect the frequency response of the system. For this radio frequency system, the negative feedback transfer function is expressed by the following formula:

[0120] ;in, is the angular frequency, is the feedback coefficient, is the open-loop gain of the amplifier.

[0121] Furthermore, resistors and capacitors are used in negative feedback loops to control the amplitude and phase of the feedback signal. Specifically, resistors control the gain of the feedback loop. Increasing the resistance reduces the amplitude of the feedback signal, thereby lowering the feedback coefficient and, in turn, affecting the closed-loop gain. Capacitors are used to adjust the system's frequency response, particularly at high frequencies. The presence of capacitors causes the gain of the system's feedback signal to vary at different frequencies, often exhibiting frequency selectivity. At low frequencies, the capacitor's effect is minimal; at high frequencies, its effect is enhanced, suppressing high-frequency noise and harmonics.

[0122] By precisely adjusting the resistance and capacitance values ​​in the negative feedback circuit, the RF system's frequency response can be optimized, system stability can be improved, noise and harmonics can be effectively suppressed, and system linearity can be enhanced. These effects are particularly important for low-noise, high-precision RF systems, ensuring higher performance and reliability within the filter band.

[0123] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A low-noise harmonic suppression radio frequency system for filter band control, characterized in that: It includes Chebyshev low-pass frequency hopping filter, weight element parameter control module, harmonic suppression module and low noise amplifier; The Chebyshev low-pass frequency hopping filter includes a plurality of weighted elements, each of which has an adjustable capacitance value and an adjustable inductance value, and the capacitance value and the inductance value of the weighted element are dynamically adjusted by the weighted element parameter control module; The input end of the Chebyshev low-pass frequency hopping filter is connected to the input end of the external radio frequency signal, and the output end thereof is connected to the input end of the harmonic suppression module; The weight element parameter control module is connected to the weight element of the Chebyshev low-pass frequency hopping filter through a multi-way selection switch, and the multi-way selection switch selects different weight element combinations according to a preset frequency switching instruction; The harmonic suppression module includes multiple harmonic suppression units. Each harmonic suppression unit suppresses harmonics in a specific frequency band through a low-pass filter and a notch filter. The harmonic suppression module is connected to the output end of the Chebyshev low-pass frequency hopping filter to further suppress harmonics on the signal output by the filter. The low-noise amplifier is connected to the output end of the harmonic suppression module and is used to perform low-noise amplification on the signal that has undergone harmonic suppression processing. A negative feedback circuit is provided inside the low-noise amplifier to compensate for nonlinear distortion during the amplification process. The input end of the low noise amplifier is connected to the output end of the harmonic suppression module, and the output end of the low noise amplifier is connected to the output end of the system.

2. A low-noise harmonic suppression radio frequency system for filter band control according to claim 1, characterized in that: The weight element parameter control module includes a central processing unit, a data storage device, a signal transceiver and a power management module; The central processing unit is connected to the data storage device via a data bus and is used to store and process frequency switching instructions and generate corresponding weight element combination selection signals according to the instructions; the signal transceiver is connected to the central processing unit and is used to receive and send instruction signals; the power management module is connected to the central processing unit and is used to manage and distribute the power provided by the power module; The weight element parameter control module is connected to the weight elements of the Chebyshev low-pass frequency hopping filter via a multi-way selection switch. The multi-way selection switch selects different weight element combinations according to preset frequency switching instructions to adjust the frequency response of the filter; the frequency response of the weight element combination is periodically calibrated to ensure the frequency response accuracy of the filter.

3. The low-noise harmonic suppression radio frequency system for filter band control according to claim 1, characterized in that: The input end of the harmonic suppression module is connected to the output end of the Chebyshev low-pass frequency hopping filter, and the output end is connected to the input end of the low-noise amplifier. The working method of the harmonic suppression module is as follows: S1: The harmonic suppression module receives the output signal from the Chebyshev low-pass frequency hopping filter and divides the signal into multiple frequency bands; S2: Perform harmonic analysis on the signal of each frequency band to determine the harmonic frequency band that needs to be suppressed; perform low-pass filtering on the main frequency band signal through a low-pass filter to remove high-frequency noise; S3: Use the notch filter to notch the harmonics in a specific frequency band and suppress the harmonic signals; S4: Merge the processed signals of each frequency band and output a signal that has undergone harmonic suppression processing.

4. A low-noise harmonic suppression radio frequency system for filter band control according to claim 3, characterized in that: The notch filter is designed by the following steps: S1: Determine the center frequency and bandwidth of the notch filter based on the harmonic frequency range of the target frequency band; S2: Design the transfer function of the notch filter so that it has maximum attenuation at the center frequency; S3: Optimize the frequency response characteristics of the notch filter by adjusting the capacitance and inductance values; S4: Combine the notch filter with the low-pass filter to form a multi-stage harmonic suppression network.

5. The low-noise harmonic suppression radio frequency system for filter band control according to claim 4, characterized in that: According to the harmonic frequency range of the target frequency band, the center frequency of the notch filter is determined by the following formula and bandwidth : ； ； in is the harmonic frequency, is the center frequency of the target frequency band.

6. A low-noise harmonic suppression radio frequency system for filter band control according to claim 5, characterized in that: Design the transfer function H(s) of the notch filter so that it is at the center frequency by the following formula: The maximum attenuation is at: ; Where Q is the quality factor, which represents the sharpness of the notch filter, s is the complex frequency variable in the Laplace transform, and Δ f is the bandwidth of the notch filter.

7. A low-noise harmonic suppression radio frequency system for filter band control according to claim 6, characterized in that: Adjust the capacitance value of the notch filter by the following formula and inductance value , optimize its frequency response characteristics: ； ； in, is the resistance value.

8. The low-noise harmonic suppression radio frequency system for filter band control according to claim 1, characterized in that: The low-noise amplifier receives the output signal from the harmonic suppression module and inputs the signal into the amplification circuit; the nonlinear distortion in the amplification process is compensated by the negative feedback circuit to ensure the linearity of the amplified signal; Perform noise suppression processing on the amplified signal to remove the noise introduced during the amplification process and output a signal that has undergone low-noise amplification processing; The negative feedback circuit design method of a low-noise amplifier includes the following steps: determining the feedback coefficient of the negative feedback circuit according to the gain requirements and nonlinear distortion characteristics of the amplifier; designing the transfer function of the negative feedback circuit so that it can effectively compensate for the nonlinear distortion during the amplification process; optimizing its frequency response characteristics by adjusting the resistance and capacitance values ​​of the negative feedback circuit; and combining the negative feedback circuit with the amplifier circuit to form a low-noise amplifier network.

9. The low-noise harmonic suppression radio frequency system for filter band control according to claim 8, characterized in that: According to the gain requirements and nonlinear distortion characteristics of the amplifier, the feedback coefficient of the negative feedback circuit is determined by the following formula: ;in, is the feedback resistor, is the input resistance, is the feedback coefficient; Designing the transfer function of a negative feedback circuit , which is expressed as follows: ;in, is the open-loop gain of the amplifier, and s is the complex frequency variable in the Laplace transform.

10. The low-noise harmonic suppression radio frequency system for filter band control according to claim 9, characterized in that: Adjust the resistance value of the negative feedback circuit by the following formula and capacitance value : ; ； in, is the angular frequency; j is the imaginary unit; It represents the frequency response function of the amplifier when no negative feedback is introduced; It represents the frequency response function of the amplifier after the negative feedback is introduced; Represents the negative feedback coefficient.

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