Low-noise harmonic suppression radio frequency system for filter band control

Abstract

The invention discloses a low-noise harmonic suppression radio frequency system for filter band control. The low-noise harmonic suppression radio frequency system comprises a Chebyshev low-pass frequency hopping filter, a power 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 power 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 with the input end of the harmonic suppression module; the power element parameter control module is connected with a power element of the Chebyshev low-pass frequency hopping filter through a multiplexer switch; the input end of the harmonic suppression module is connected with the output end of the Chebyshev low-pass frequency hopping filter; the low noise amplifier is connected with the output end of the harmonic suppression module; the input end of the low-noise amplifier is connected with the output end of the harmonic suppression module. Through cooperative work of the modules, radio frequency signals can be efficiently processed, and the targets of frequency band control, harmonic suppression and noise suppression are 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. Although existing harmonic suppression technologies can meet basic needs to a certain extent, they still have many shortcomings in multi-band and wide dynamic range application scenarios. For example, existing harmonic suppression schemes often rely on complex filter groups and band control circuits, which leads to larger system size and increased costs, and it is difficult to achieve efficient harmonic suppression and low noise performance.

[0003] After searching, a harmonic suppression method and a corresponding low-noise amplifier and communication terminal were disclosed with a publication number of CN106160673B, and the publication date was March 30, 2021. This technology improves the design flexibility of the signal amplification circuit by setting an isolation unit between the harmonic suppression unit and the output matching network / input matching network of the low-noise amplifier. However, this solution is mainly aimed at harmonic suppression of a single frequency band, and does not involve the band control problem of multi-band filters. In addition, the design of the isolation unit increases the complexity of the circuit, making it difficult to achieve efficient harmonic suppression and low noise performance in wide-band applications.

[0004] After searching, a broadband harmonic suppression amplifier with a publication number of CN114172464B was disclosed, and the publication date is May 24, 2022. This technology adopts broadband current multiplexing and common source amplification network, combined with a gate-source RLC parallel negative feedback circuit, to achieve the characteristics of wide bandwidth, high gain and low power consumption. Although this scheme has improved broadband harmonic suppression, the design of its harmonic suppression equalization matching network is complex, and it is not optimized for filter band control, making it difficult to achieve efficient harmonic suppression and low noise performance in multi-band applications.

[0005] The above problems show that the existing harmonic suppression technology has problems such as complex design and insufficient performance in the filter band control system with multi-band and wide dynamic range. Therefore, the present invention provides a low-noise harmonic suppression radio frequency system for filter band control to overcome these shortcomings and provide a new solution that is more efficient, flexible and adaptable to 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 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 value and an inductance value. The capacitance value and the inductance value of the weighted element are dynamically adjusted through a weighted element parameter control module to achieve frequency response switching of multiple frequency bands.

[0010] The external RF signal is used as the input of the Chebyshev low-pass frequency hopping filter, and the output end of the external RF signal 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 a plurality of harmonic suppression units, each of which suppresses harmonics in a specific frequency band through a low-pass filter and a notch filter, and the input end of the harmonic suppression module of the harmonic suppression module is connected to the output end of the Chebyshev low-pass frequency hopping filter, so as to further perform harmonic suppression processing 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 been processed by the harmonic suppression. A negative feedback circuit is provided inside the low noise amplifier to compensate for the 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 through the data bus, and is used to store and process the 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 element of the Chebyshev low-pass frequency hopping filter through a multi-way selection switch. 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.

[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 notch filters to notch the harmonics in a specific frequency band and suppress harmonic signals;

[0022] S4: Combine the processed signals of each frequency band and output a signal after 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 according to the harmonic frequency range of the target frequency band;

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

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

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

[0028] Preferably, according to the harmonic frequency range of the target frequency band, the center frequency f of the notch filter is determined by the following formula: 0 And bandwidth Δf:

[0029]

[0030] Δf=f harmonic -f target ;

[0031] where f harmonic is the harmonic frequency, f targetis the center frequency of the target frequency band.

[0032] Preferably, the transfer function H(s) of the notch filter is designed so that the transfer function at the center frequency f is 0 The maximum attenuation is at:

[0033]

[0034] 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.

[0035] Preferably, the capacitance value C and the inductance value L of the notch filter are adjusted by the following formula to optimize the transfer function frequency response characteristics:

[0036]

[0037] Where R is the resistance value.

[0038] 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 signal subjected to the low noise amplification processing is output;

[0039] The design of the negative feedback circuit 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 the frequency response characteristics of the transfer function by adjusting the resistance and capacitance values ​​of the negative feedback circuit; combining the negative feedback circuit with the amplifier circuit to form a low-noise amplifier network.

[0040] 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: Among them, R f is the feedback resistor, R i is the input resistance.

[0041] Preferably, the transfer function A of the negative feedback circuit is designed f (s), which is expressed as follows:

[0042] Where A(s) is the open-loop gain of the amplifier.

[0043] Preferably, the resistance value R and the capacitance value C of the negative feedback circuit are adjusted by the following formula:

[0044]

[0045]

[0046] Where ω is the angular frequency and j is the imaginary unit;

[0047] A f (jω) represents the frequency response function of the amplifier when no negative feedback is introduced;

[0048] A FB (jω) represents the frequency response function of the amplifier after the introduction of negative feedback;

[0049] β(jω) represents the negative feedback coefficient.

[0050] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0051] 1. Through the coordinated work of Chebyshev low-pass frequency hopping filter, weight element parameter control module, harmonic suppression module and low noise amplifier, it can efficiently process RF signals and achieve the goals of frequency band control, harmonic suppression and noise suppression.

[0052] 2. By controlling the parameters of the weighted components through the central processor and combining the flexible switching of the multi-way selector switch, the system can adjust the operating frequency response of the filter in real time and accurately to meet the requirements of different application scenarios. This flexibility enables the RF system to work stably within a wide frequency band and avoid performance loss caused by fixed frequency band restrictions.

[0053] 3. Through precise frequency band division and harmonic suppression, the system can effectively remove interference from high-frequency noise and unnecessary harmonic components to maintain signal purity. This is especially important for high-demand RF applications and can significantly improve the system's signal-to-noise ratio and overall performance.

[0054] 4. The design of the notch filter ensures deep attenuation of harmonic interference of specific frequencies without significantly affecting the main signal frequency. By adjusting the capacitance and inductance values, the frequency response can be optimized to ensure that no signal distortion occurs during signal transmission and the main signal can remain clear and stable.

[0055] 5. By designing the transfer function, the maximum attenuation can be achieved at the center frequency, thus 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 by higher harmonics. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] 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:

[0057] Figure 1 It is a structural block diagram of the system of the present invention. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and drawings. The schematic implementation modes and descriptions of the present invention 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.

[0059] See also Figure 1 The embodiment of the present invention provides a low-noise harmonic suppression radio frequency system for filter band control, including 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 includes 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; an external radio frequency signal is used as an 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 element of the Chebyshev low-pass frequency hopping filter through a multi-way selection switch, and the multi-way selection switch is adjusted according to a preset frequency The switching instruction 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 input end of the harmonic suppression module is connected to the output end of the Chebyshev low-pass frequency hopping filter, which is used to perform further harmonic suppression processing on the signal output by the filter; the low-noise amplifier is connected to the output end of the harmonic suppression module, which is used to perform low-noise amplification on the signal after harmonic suppression processing, and a negative feedback circuit is arranged inside the low-noise amplifier to compensate for nonlinear distortion in 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.

[0060] In a possible implementation, the Chebyshev low-pass frequency hopping filter, as the core of the system, can dynamically switch the filtering characteristics according to the frequency band requirements of the input signal. It is composed of multiple weight elements. The capacitance and inductance values ​​of each weight element can be adjusted by the weight element parameter control module. Specifically, the parameter control module controls different combinations of capacitance and inductance through a multi-way selection switch, thereby changing the cutoff frequency of the filter, allowing the filter to switch between multiple frequency bands as needed. This dynamic adjustment can ensure that the frequency response of the signal meets different application requirements and avoids performance loss due to fixed frequency bands.

[0061] Furthermore, the weight element parameter control module can accurately control the capacitance and inductance values ​​of each weight element by connecting to the Chebyshev low-pass frequency hopping filter. Specifically, the control module selects different combinations of capacitance and inductance values ​​through a multi-way selection switch to achieve a preset frequency response. The frequency switching instructions for each frequency band will result in different combinations of capacitance and inductance, thereby adjusting the working state of the filter. This switching can effectively support complex RF applications and ensure that the signal can be properly filtered in different frequency bands.

[0062] Furthermore, after the Chebyshev filter outputs the signal, the harmonic suppression module further improves the signal quality. The module includes multiple harmonic suppression units, each of which uses a low-pass filter and a notch filter to suppress harmonics in a specific frequency band. The low-pass filter can eliminate 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 output signal, thereby improving the overall performance of the RF system.

[0063] Finally, the low noise amplifier performs low noise amplification on the harmonically suppressed signal to enhance the signal strength. Inside the low noise amplifier, a negative feedback circuit is designed to compensate for the nonlinear distortion during the amplification process and ensure the quality of the output signal. The use of a low noise amplifier can ensure that the noise gain is minimized during the signal processing process and provide a more stable and clear signal output. This amplification process is particularly important for RF systems because it not only needs to increase the power of the signal, but also must ensure that the noise level is suppressed during the gain process.

[0064] Through the above design, this low-noise harmonic suppression RF system provides flexible frequency switching capabilities in multiple frequency bands, while effectively suppressing high-order harmonics and noise. The dynamic adjustment of the weight element parameter control module enables the system to automatically optimize the frequency response according to different application scenarios, ensuring the adaptability of the system within a wide frequency band. The designs of the harmonic suppression module and the low-noise amplifier complement each other, jointly ensuring the improvement of signal quality, reducing nonlinear distortion and noise, and ultimately outputting high-quality RF signals. In addition, the setting of the negative feedback circuit further reduces the distortion during the amplification process and ensures the linear response of the system.

[0065] 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 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 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 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.

[0066] In one possible implementation, the design and function of the weight element parameter control module ensures the dynamic adjustment and high-precision calibration of the frequency response of the Chebyshev low-pass frequency hopping filter through precise signal control and power management. Specifically, the weight element parameter control module includes a central processing unit, a data storage device, a signal transceiver, and a power management module. These components are interconnected through a data bus and a signal interface, and work together to ensure that the system can flexibly and efficiently adjust the operating frequency of the filter according to different application scenarios or requirements.

[0067] Specifically, the central processing unit is responsible for receiving external instructions and processing these instructions. Through the data bus connected to the data memory, the central processing unit can obtain frequency switching instructions and filter operating parameters from the memory. These instructions and parameters include the combination of capacitors and inductors required for frequency band switching and other configuration data.

[0068] Furthermore, the signal transceiver, as an input and output interface, can communicate with external devices or systems. It sends the frequency switching instructions generated by the central processor to the external device and receives feedback signals to ensure that the instructions are executed correctly. The signal transceiver plays the role of a bridge for instruction transmission in the entire system.

[0069] Furthermore, the power management module is responsible for monitoring and allocating the power required within the system to ensure that the various components in the system, especially the central processing unit, signal transceiver and multi-way selection switch, can operate stably. It allocates power according to the needs of the central processing unit to ensure the stability and efficiency of the power supply of the system during operation.

[0070] Furthermore, in the specific filter operation process, the multi-way selection switch selects different weight component combinations according to the selection signal generated by the central processor, thereby adjusting the frequency response of the Chebyshev low-pass frequency hopping filter. By dynamically adjusting the combination of these components, the system can switch the frequency so that the operating frequency response of the filter can adapt to different application requirements.

[0071] In order to ensure that the frequency response of the Chebyshev filter always maintains high accuracy, the system periodically calibrates the frequency response of the weight component combination. The calibration process obtains real-time feedback through the central processor and sensors, adjusts the parameters of the weight components, and ensures that the accuracy of the filter when switching frequency bands is not affected by the external environment or component aging.

[0072] 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: harmonics of a specific frequency band are notched by a notch filter to suppress harmonic signals; S4: the processed signals of each frequency band are merged and the signal after harmonic suppression is output.

[0073] In a possible implementation, the input end of the harmonic suppression module is connected to the output end of the Chebyshev low-pass frequency hopping filter. The Chebyshev low-pass frequency hopping filter is responsible for extracting the main frequency band signal from the input signal and removing some unnecessary frequency components. The harmonic suppression module provides filtered frequency components for subsequent harmonic analysis and processing by receiving the output signal.

[0074] Furthermore, the harmonic suppression module first divides the received signal into multiple frequency bands. The key to this process is accurate signal segmentation so that each frequency band can be processed separately. The individual frequency bands after signal segmentation can be more easily analyzed for subsequent harmonics to avoid interference between different frequency bands.

[0075] Furthermore, each segmented frequency band signal will undergo harmonic analysis to identify which frequency bands have harmonic interference. For the main frequency band signal, the system uses a low-pass filter to perform low-pass filtering to remove high-frequency noise and keep the signal spectrum pure. In this process, the low-pass filter mainly filters out noise components that exceed a certain frequency threshold and retains useful signal frequencies.

[0076] For the harmonic frequency bands that need to be suppressed, the harmonic suppression module performs special notch processing through notch filters. The function of notch filters is to accurately remove signals within certain specific frequency ranges, which are usually spurious frequencies generated by harmonic effects. Through precise frequency positioning, notch filters can effectively suppress these harmonic components, thereby avoiding their influence on other parts of the system.

[0077] Finally, the processed signals of each frequency band are combined to form an overall output signal after harmonic suppression. This signal is sent to the input of the low noise amplifier to ensure that the signal quality is maintained throughout the RF system.

[0078] 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 according to the harmonic frequency range of the target frequency band; S2: designing the transfer function of the notch filter so that the transfer function has maximum attenuation at the center frequency; S3: optimizing the frequency response characteristics of the transfer function 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.

[0079] In one possible implementation, the design of the notch filter starts with determining the harmonic frequency range of the target frequency band. Usually, harmonic interference is caused by nonlinear effects in the input signal, and the generated harmonics are usually located at integer multiples of the input signal frequency. Therefore, the designer first needs to calculate the possible harmonic frequencies based on the main frequency band of the input signal in the system. Based on this information, the designer can choose the appropriate center frequency and bandwidth to effectively suppress these harmonics.

[0080] In this application, "target frequency band" refers to the specific frequency range where the main signal frequency of the RF system is located. This frequency band is the core frequency area of ​​concern when designing the system, which contains the main signal components, and the harmonic frequencies are integer multiples of the main frequency band frequency.

[0081] Furthermore, after determining the center frequency and bandwidth, the designer needs to design the transfer function of the notch filter to ensure that it has maximum attenuation at the specified center frequency. The purpose of designing the transfer function is to ensure that the filter can produce deep attenuation in the harmonic frequency range while remaining transparent to signals in other frequency bands. During design, the performance of the filter can be optimized by adjusting the quality factor and bandwidth of the filter.

[0082] Furthermore, the core components of the notch filter are usually capacitors and inductors, so during the design process, it is necessary to optimize the frequency response characteristics of the filter by adjusting the capacitor and inductor values. The specific values ​​of the inductor and capacitor determine the center frequency and bandwidth range of the filter, so through precise calculation and debugging, it can be ensured that the filter effectively suppresses harmonics within the required frequency range while avoiding the impact on the main frequency band signal.

[0083] 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 can effectively filter out high-frequency noise, while the notch filter is specifically designed to deeply attenuate specific harmonics. After the two are combined, the system can achieve more accurate signal processing. The low-pass filter is usually placed at the front end to remove high-frequency noise, while the notch filter is placed at the back end as needed to remove harmonics of specific frequencies.

[0084] In the embodiment of the present invention, according to the harmonic frequency range of the target frequency band, the center frequency f of the notch filter is determined by the following formula: 0 And bandwidth Δf:

[0085]

[0086] Δf=f harmonic -f target ;

[0087] where f harmonic is the harmonic frequency, f target is the center frequency of the target frequency band.

[0088] In a possible implementation, first, the operating frequency band of the radio frequency system, that is, the target frequency band f target . Usually, in a radio frequency system, 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 of the target frequency band is f target , then the harmonics may appear at 2f target 、3f target 、4f target Equal frequency.

[0089] According to the given formula, the center frequency and bandwidth of the notch filter can be calculated by the following steps:

[0090] Center frequency f 0 Calculated as the average of the center frequency and harmonic frequencies of the target frequency band: This calculation method means that the notch filter design will locate an appropriate center frequency between the target frequency band and the harmonic frequencies, thereby accurately suppressing harmonic interference.

[0091] The bandwidth Δf is determined by the difference between the target frequency band and the harmonic frequency: Δf = f harmonic -f target ; 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.

[0092] Once the center frequency and bandwidth are determined, the designer can adjust the circuit structure of the notch filter according to these parameters and select appropriate inductor and capacitor components to achieve the desired frequency response. Typically, the notch filter optimizes the 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.

[0093] In practical applications, notch filters usually work together with other filters (such as low-pass filters) to form a multi-stage filtering network. Low-pass filters are usually used to remove high-frequency noise above the target frequency band, while notch filters are specifically designed to deeply attenuate harmonics. Through the coordinated work of multi-stage filtering, the system can effectively remove harmonic interference without distorting the target signal.

[0094] In the embodiment of the present invention, the transfer function H(s) of the notch filter is designed to make the transfer function at the center frequency f 0 The maximum attenuation is at:

[0095]

[0096] 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.

[0097] In a possible implementation, first, based on the analysis of the target frequency band and the harmonic frequency band, the designer determines the center frequency f of the notch filter. 0 and bandwidth Δf. The center frequency is usually chosen as 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.

[0098] The quality factor determines the sharpness of the filter and indicates the frequency selectivity of the filter. A higher Q value means that the filter has a narrower bandwidth at the center frequency and a more obvious suppression effect. When designing, it is necessary to select a suitable Q value based on the actual harmonic frequency characteristics and system needs.

[0099] Once f is determined 0 , Δf and Q, 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.

[0100] In analog circuit design, the transfer function H(s) is converted into a combination of specific 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.

[0101] By designing the transfer function, the maximum attenuation can be achieved at the center frequency, thus 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 by high-order harmonics.

[0102] In the embodiment of the present invention, the capacitance value C and the inductance value L of the notch filter are adjusted by the following formula to optimize the frequency response characteristic of the transfer function:

[0103]

[0104] Where R is the resistance value.

[0105] In a possible implementation, according to the required harmonic suppression frequency, the center frequency f is first determined. 0 , which is the frequency point near the target signal frequency. Then, calculate the appropriate capacitance value C and inductance value L based on the selected center frequency and formula.

[0106] Furthermore, in order to achieve efficient harmonic suppression, the bandwidth of the filter needs to be adjusted, which can be achieved by adjusting the resistance and inductance. The narrower the bandwidth, the more selective the filter is to the center frequency, and the target harmonics can be suppressed more accurately without affecting other signals. By adjusting the inductance and resistance, the desired bandwidth can be achieved.

[0107] In actual circuits, capacitors, inductors, and resistors are combined to form the core components of notch filters. The values ​​of capacitors and inductors will determine the frequency response of the filter, while resistors affect the bandwidth and the quality factor (Q value) of the filter. By adjusting the values ​​of these components, the frequency response of the filter can be precisely controlled to have maximum attenuation within the target frequency band.

[0108] By adjusting the values ​​of inductance and capacitance, the center frequency of the notch filter can be accurately controlled to ensure the filter's suppression effect on the target harmonics. The precise control of the harmonic frequency position enables the system to effectively filter out unwanted high-order harmonics without affecting the main signal.

[0109] 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 amplifier circuit; nonlinear distortion in the amplification process is compensated by a negative feedback circuit to ensure the linearity of the amplified signal; noise suppression processing is performed on the amplified signal to remove the noise introduced in the amplification process, and a signal after low-noise amplification processing is output; the negative feedback circuit design of the low-noise amplifier includes the following steps: determining a feedback coefficient of the negative feedback circuit according to the gain requirement 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 the transfer function frequency response characteristics by adjusting the resistance value and capacitance value of the negative feedback circuit; combining the negative feedback circuit with the amplifier circuit to form a low-noise amplifier network.

[0110] In the embodiment of the present invention, first, the feedback coefficient required by the negative feedback circuit is determined according to the gain requirement and the requirement for nonlinear distortion of the low noise amplifier. The gain requirement determines the basic gain of the amplifier, while the nonlinear distortion characteristic affects the fidelity of the signal. Generally, too high a gain is likely to cause nonlinear distortion, so it is necessary to balance the gain and distortion during design.

[0111] The transfer function of the negative feedback circuit determines the amplitude and phase characteristics of the feedback signal. The negative feedback network is designed based on this transfer function so that it can effectively compensate for the nonlinear distortion generated in the amplifier. Negative feedback can suppress high-order harmonic components by reducing the gain of the amplifier, making the signal more linear.

[0112] Furthermore, the transfer function frequency response characteristics are optimized by adjusting the resistance and capacitance values ​​in the negative feedback circuit. The selection 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.

[0113] After the design is completed, 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, so that the gain is adjusted and the nonlinear distortion is compensated through the feedback loop.

[0114] 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.

[0115] In the embodiment of the present invention, 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: Among them, R f is the feedback resistor, Ri is the input resistance.

[0116] In a possible implementation, during the design process, it is first necessary to analyze the gain requirements of the low noise amplifier and the system's requirements for nonlinear distortion. Excessive gain can easily introduce nonlinear distortion, and appropriate negative feedback can effectively reduce this distortion. By selecting an appropriate feedback factor, the system can suppress the generation of high-order harmonics while maintaining the desired gain.

[0117] Furthermore, according to the feedback coefficient formula, the designer can choose the appropriate ratio of feedback resistance to input resistance. This ratio determines the closed-loop gain of the amplifier and affects its frequency response and nonlinear characteristics. Specifically, the feedback resistor adjusts the gain and reduces nonlinear distortion by feeding back part of the output signal to the input. The input resistance determines the interaction between the impedance of the input signal and the feedback signal.

[0118] In actual circuits, feedback resistors are usually connected between the output and input of the amplifier to form a closed loop. Through this connection, part of the amplifier's output signal is fed back to the input, thereby adjusting the gain and making the amplifier's gain more stable. The input resistor is usually connected to the input of the amplifier, and together with the feedback circuit, it affects the signal processing process.

[0119] 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.

[0120] In the embodiment of the present invention, the transfer function A of the negative feedback circuit is designed. f (s), which is expressed as follows:

[0121] Where A(s) is the open-loop gain of the amplifier.

[0122] In one possible implementation, the open-loop gain of an amplifier is the gain of the amplifier to the input signal without any feedback loop. When designing a low-noise harmonic suppression RF system, the open-loop gain is usually a high value, but may result in an unsatisfactory frequency response due to nonlinear distortion or excessive gain, so it needs to be optimized through a negative feedback circuit.

[0123] Furthermore, the negative feedback circuit usually includes a feedback resistor and an input resistor. The feedback signal is fed back from the output end of the amplifier to the input end, forming a closed loop. The feedback coefficient determines the amplitude of the feedback signal, which is determined by the feedback resistor and the input resistor. The output signal is input to the input end of the amplifier through the feedback resistor, and the input signal acts together with the feedback signal through the input resistor.

[0124] By designing an appropriate negative feedback circuit and utilizing its transfer function, harmonics can be effectively suppressed, the linearity and frequency response of the system can be improved, and the stability and reliability of the system can be enhanced, thereby optimizing the overall performance of the RF system, especially in filter band control.

[0125] In the embodiment of the present invention, the resistance value R and the capacitance value C of the negative feedback circuit are adjusted by the following formula:

[0126]

[0127]

[0128] Where ω is the angular frequency and j is the imaginary unit;

[0129] A f (jω) represents the frequency response function of the amplifier when no negative feedback is introduced;

[0130] A FB (jω) represents the frequency response function of the amplifier after the introduction of negative feedback;

[0131] β(jω) represents the negative feedback coefficient.

[0132] Furthermore, resistors and capacitors are used in negative feedback loops to control the amplitude and phase of the feedback signal. Specifically, resistors are used to control the gain of the feedback loop. Increasing the resistor will reduce the amplitude of the feedback signal, thereby reducing the feedback factor, which in turn affects the closed-loop gain. Capacitors are used to adjust the frequency response of the system, especially the high-frequency response. The presence of capacitors causes the gain of the system's feedback signal to change at different frequencies, and is usually frequency selective. At low frequencies, the effect of capacitors is small; at high frequencies, the effect of capacitors is enhanced, which can suppress high-frequency noise and harmonics.

[0133] By precisely adjusting the resistance and capacitance values ​​in the negative feedback circuit, the frequency response of the RF system can be optimized, the stability of the system can be improved, noise and harmonics can be effectively suppressed, and the linearity of the system can be improved. These effects are especially important for low-noise, high-precision RF systems, which can ensure that the system has higher performance and reliability within the filter band.

[0134] 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 a Chebyshev low-pass frequency hopping filter, a weight element parameter control module, a harmonic suppression module and a 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 inductance value, and the capacitance value and the inductance value of the weighted element are dynamically adjusted through the weighted element parameter control module; The external RF signal is used as the input of the Chebyshev low-pass frequency hopping filter, and the output end of the external RF signal 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 a plurality of harmonic suppression units, each of which suppresses harmonics in a specific frequency band through a low-pass filter and a notch filter, and the input end of the harmonic suppression module of the harmonic suppression module is connected to the output end of the Chebyshev low-pass frequency hopping filter, so as to further perform harmonic suppression processing 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 been processed by the harmonic suppression. A negative feedback circuit is provided inside the low noise amplifier to compensate for the nonlinear distortion during the amplification process. The output terminal of the low noise amplifier is connected to the output terminal 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 through the data bus, and is used to store and process the 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 element of the Chebyshev low-pass frequency hopping filter through a multi-way selection switch. The multi-way selection switch selects different weight element combinations according to preset frequency switching instructions and periodically calibrates the frequency response of the weight element combination.

3. A low-noise harmonic suppression radio frequency system for filter band control according to claim 1, characterized in that: The working method of the harmonic suppression module is: 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 notch filters to notch the harmonics in a specific frequency band and suppress harmonic signals; S4: Combine the processed signals of each frequency band and output a signal after 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 according to the harmonic frequency range of the target frequency band; S2: Design the transfer function of the notch filter so that the transfer function has maximum attenuation at the center frequency; S3: Optimize the transfer function frequency response characteristics by adjusting the capacitance and inductance values ​​of the notch filter; S4: Combine the notch filter with the low-pass filter to form a multi-stage harmonic suppression network.

5. A 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 f0 and bandwidth Δf of the notch filter are determined by the following formula: Δf=f harmonic -f target ; where f harmonic is the harmonic frequency, f target 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 the transfer function has maximum attenuation at the center frequency f0 by the following formula: 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.

7. A low-noise harmonic suppression radio frequency system for filter band control according to claim 6, characterized in that: The transfer function frequency response characteristics can be optimized by adjusting the capacitance value C and the inductance value L of the notch filter through the following formula: Where R is the resistance value.

8. A 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 design of the negative feedback circuit 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 to compensate for the nonlinear distortion during the amplification process; optimizing the frequency response characteristics of the transfer function by adjusting the resistance and capacitance values ​​of the negative feedback circuit; combining the negative feedback circuit with the amplifier circuit to form a low-noise amplifier network.

9. A 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: Among them, R f is the feedback resistor, R i is the input resistance, β is the feedback coefficient; Design the transfer function of the negative feedback circuit A f (s), which is expressed as follows: Where A(s) is the open-loop gain of the amplifier and s is the complex frequency variable in the Laplace transform.

10. A low-noise harmonic suppression radio frequency system for filter band control according to claim 9, characterized in that: Adjust the resistance value R and capacitance value C of the negative feedback circuit by the following formula: Where ω is the angular frequency and j is the imaginary unit; A f (jω) represents the frequency response function of the amplifier when no negative feedback is introduced; A FB (jω) represents the frequency response function of the amplifier after the introduction of negative feedback; β(jω) represents the negative feedback coefficient.

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