56 results about "Impedance network" patented technology

The invention discloses an electrical safety test data analysis method and system for an electrical cabinet, and relates to the technical field of electrical measurement and test. The method is used for solving the problems of single test dimension, poor anti-interference capability and inaccurate fault positioning in the safety test of the electrical cabinet. Firstly, multi-channel electrical parameter synchronous acquisition is triggered based on a working condition event, real discharge and interference signals are distinguished through time-frequency analysis, and a time sequence incidence matrix of discharge pulses and load currents is established; then, analyzing phase distribution characteristics of partial discharge, calculating a correlation coefficient between a discharge repetition rate and a load current, and dynamically adjusting a weight to generate an insulation state comprehensive test index; further, insulation degradation characteristics are extracted through signal decomposition, and an insulation degradation trend and a fault probability are predicted in combination with energy entropy analysis and discharge mode recognition; and finally, the position of a fault component is analyzed and positioned based on the impedance network, and a maintenance priority sequence is generated according to the fault probability and the degradation rate.

The application discloses a charged water body equivalent impedance model construction and parameter acquisition method and related devices, and innovatively establishes a calculation system containing resistance and inductance correction factors, and realizes high-precision characterization of water body impedance characteristics by introducing an electrode spacing function. Specifically, a scalable grid technology is used to construct an adaptive calculation framework, and the calculation accuracy of resistance and inductance parameters is significantly improved through a power function correction algorithm. A reliable numerical calculation is provided for water body impedance network model analysis in complex hydrological environments. The application solves the problems of the prior art, such as complex modeling process, difficulty in accurately describing nonlinear behavior, insufficient precision, and inability to accurately capture the real behavior of water body.

The application discloses a power converter, a power supply system, a control method and related devices. The power converter comprises an impedance network and a three-phase power conversion circuit, each phase of the three-phase power conversion circuit comprising a four-switch Buck-Boost circuit; the DC side of the three-phase power conversion circuit is used for connecting a DC source, and the AC side of the three-phase power conversion circuit is used for connecting a load or a power grid; wherein the load adopts star connection, and the power grid adopts star connection; the first end of the impedance network is connected to the positive pole of the DC side of the three-phase power conversion circuit, and the second end of the impedance network is used for connecting the neutral point of the load or the neutral point of the power grid. In the embodiment of the application, in the case that the power converter is switched from three-phase three-wire system to three-phase four-wire system, the impedance network is connected between the N line (the DC side of the three-phase power conversion circuit and the neutral point of the load or the neutral point of the power grid), the inrush current on the N line is reduced, and the risk of damage of the switching device in the power converter is reduced.

The invention belongs to the technical field of integrated circuit design, and particularly discloses a low-delay sampler structure and method for high-speed data processing, and in a pseudo reset stage, an unlocking network module and a pre-latching network module are connected in parallel to form an equivalent low-impedance network unit; the transconductance module is used for inputting a sampling signal and a reference level signal and driving the equivalent low-impedance network unit; the pre-latch network module is used for enabling an output node of the pre-latch network module to start charging and discharging according to a sampling signal and a reference level signal and pre-sampling the sampling signal; meanwhile, in the latching stage, the transconductance module is used for driving the pre-latching network module to preliminarily amplify the sampling signal, and the strong latching network module is used for stably latching the sampling signal under the driving of the pre-latching network module. According to the invention, the sampling delay of the signal is obviously shortened, and meanwhile, the requirement of high-speed data processing on the time sequence progress is met.

The invention provides a high-stability control method for a power grid simulator, and the method comprises the steps: embedding a virtual impedance feature Zvirref (s) in an integral controller of a voltage controller module, and forming a controller structure of Ki * Zvirref (s) / s; and dynamically adjusting the integral gain Ki according to the virtual impedance generated by the power grid simulator and the physical impedance provided by the impedance network B so as to meet the condition that the amplitude of the virtual impedance is not higher than the amplitude of the physical impedance in the frequency range in which the virtual impedance is presented to be non-passive. Decoupling between internal control dynamic and virtual impedance characteristics of the power grid simulator is realized, and the self-stability of the power grid simulator under different impedance simulation conditions is ensured; the self-adaptive adjustment of the closed-loop transfer function of the power grid simulator is realized, the virtual impedance and the physical impedance are ensured to meet the Nyquist stability criterion, and the interaction stability between the power grid simulator and the tested object is improved.

The present application relates to the technical field of probe card signal optimization, in particular to a high-frequency probe card signal optimization method based on dynamic impedance matching and related devices. The method steps include: obtaining real-time high-frequency signal reflection parameters of the probe card test channel to provide real-time detection basis for dynamic impedance matching. The present application relies on the real-time acquisition of the high-frequency signal reflection parameters of the probe card test channel to complete the quantitative tracing of the dynamic impedance deviation, and through the closed-loop feedback adjustment, the integrated adjustable impedance network of the driving probe is used to complete the real-time correction of the output impedance. From the root level of transmission line impedance matching, the present application breaks through the inherent limitation of the traditional static matching scheme which can only adapt to the nominal working condition, and can effectively offset the dynamic impedance mismatch introduced by the contact state difference, the probe structure micro-deformation, the device individual parasitic parameter dispersion and the nonlinear evolution of the parasitic parameters under high frequency in the actual test process, and solves the reflection residual problem that cannot be eliminated by static matching.

The application belongs to the technical field of wireless communication, and discloses a backscattering communication method, device and system based on multi-carrier differential modulation t The transmission vector at t-1 time is expanded into a symmetric and full-rank subcarrier block transmission matrix, the transmission vector u t is subjected to rectangular differential modulation to obtain the transmission vector at t time, and then is converted into a time-domain data frame and mapped into a reflection coefficient; and the excitation source signal is modulated by means of an impedance network to generate a backscattering signal. Since differential modulation transmits information based on the difference between adjacent symbols, the channel state information is cancelled in the process of data detection at the receiving end, and the original sending data can be recovered by non-coherent detection of the receiving signal at the receiving end, without a complex cascaded channel estimation process, so that the complexity of the multi-carrier backscattering communication system is effectively reduced.

The invention relates to the technical field of bioelectrical impedance testers, in particular to a calibration device of a bioelectrical impedance tester and a calibration method thereof. According to the technical scheme, the calibration device of the bioelectrical impedance tester is connected with a host of the bioelectrical impedance tester through a communication interface and a calibration port, and comprises a main control unit used for communicating with the host of the tester and analyzing an instruction from the host; the control end of the high-speed multiplexer is connected with the main control unit, and the output end of the high-speed multiplexer is connected to the calibration port; the standard impedance network is composed of a plurality of high-precision passive elements and comprises resistors, capacitors, inductors and series-parallel combinations of the resistors, the capacitors and the inductors, and the impedance elements are connected to different input channels of the high-speed multiplexer respectively. Through a highly integrated standard impedance network and an automatic switching mechanism, full automation of a calibration process is realized, manual errors are thoroughly eliminated, and calibration efficiency and consistency are greatly improved.

The present disclosure relates to a digital-to-analog converter comprising an impedance network and a transfer function modification circuit. The transfer function modification circuit comprises a DAC and a demultiplexer. The demultiplexer may be used to selectively connect the output of the DAC to different respective nodes of the impedance network, allowing positive or negative currents to be injected into the node and modify the transfer function. By using a demultiplexer to selectively couple to different nodes, the node into which the current is injected may be modified post-manufacture, allowing transfer function modification.

The invention discloses a test platform for simulating photovoltaic direct-current fault arc waveforms. The test platform comprises a simulation optical direct-current fault arc waveform test platform cabinet, a simulation photovoltaic direct-current power supply cabinet, a decoupling device cabinet, an impedance network cabinet, a simulation arc cabinet, a product test cabinet and a photovoltaic power supply inverter cabinet. The test platform simulates a photovoltaic direct current power supply, a decoupling and impedance network and a fault arc; an industrial personal computer system is used for automatically capturing signals for testing, and fault arc waveform signals are restored in real time; multi-point automatic measurement acquisition, analysis and comparison are carried out on test signals; multiple key parameters related to the fault arc are displayed in real time based on a touch screen, and finally a test conclusion, a specific numerical value of response time, a judgment basis and all waveforms and analysis data are integrated into a final test report to be output. According to the invention, a traditional oscilloscope can be replaced to observe waveforms, and high-precision performance testing of photovoltaic protection products can be realized in all directions.

The application belongs to the technical field of audio power amplifier filtering, and particularly relates to a band-pass filter circuit for eliminating radio frequency interference of an audio power amplifier. The band-pass filter circuit comprises an operational amplifier AMP, a reference voltage BYP connected to a non-inverting input terminal of the operational amplifier AMP, an input impedance network connected between an audio input terminal IN grounded and an inverting input terminal of the operational amplifier AMP, and a feedback impedance network connected between an output terminal and the inverting input terminal of the operational amplifier AMP. The feedback impedance network is composed of two parallel feedback branches. A first feedback branch is composed of a resistor R2, and a second feedback branch is composed of a resistor R3 and a capacitor C2 connected in series. A zero point is introduced in a transfer function of the band-pass filter circuit, and a zero point frequency is determined by a resistance value of the resistor R3 and a capacitance value of the capacitor C2, so as to suppress a gain near the zero point frequency, thereby effectively suppressing interference of high-frequency noise.

This invention relates to the field of bioelectrical impedance analysis (BIA) technology, and more particularly to a calibration device and method for a BIA. The technical solution is as follows: A calibration device for a BIA, the device being connected to a BIA host via a communication interface and a calibration port. The device includes: a main control unit for communicating with the host and parsing instructions from the host; a high-speed multiplexer, the control terminal of which is connected to the main control unit, and the output terminal connected to the calibration port; and a standard impedance network composed of multiple high-precision passive components, including resistors, capacitors, inductors, and their series-parallel combinations, wherein each impedance component is connected to a different input channel of the high-speed multiplexer. Through a highly integrated standard impedance network and an automatic switching mechanism, the calibration process is fully automated, completely eliminating human error and greatly improving calibration efficiency and consistency.

The present application relates to the technical field of power system, discloses a kind of multi-level DC sending end small signal stability evaluation method, device, equipment and medium, the present application considers the coupling influence between different heterogeneous devices, to network type new energy converter, network type energy storage converter, network type load converter and modular multi-level high voltage direct current converter station are carried out frequency domain impedance modeling, and based on the equivalent impedance model of each device, the frequency domain impedance network of all-electric system is constructed, the small signal stability of frequency domain impedance network is analyzed using generalized Nyquist stability criterion, the Nyquist diagram of impedance ratio on the two sides of voltage source and current source in frequency domain impedance network is determined The small signal stability of all-electric system under AC / DC hybrid scene, so as to provide an effective evaluation means for the stable operation of AC / DC hybrid all-electric system.

The application discloses an inverter stability optimization control method based on PLL link parameter adjustment. Firstly, the inverter, grid impedance network and the like are introduced into a phase-locked loop in the form of coupled interference of port characteristics, and a synchronous dynamic mathematical expression of the phase-locked loop and the coupled interference is established; secondly, according to the coupling relationship of the PLL in the system, a dynamic control equation of the inverter is determined. Then, based on the PLL dominant loop, the system stability is determined through the phase margin of the equation at the crossing frequency; finally, by adding a transfer function H(s) in series in the PLL to change the loop characteristics of the PLL, parameter design is carried out for the control optimization method of the PLL in different control modes; the application can clearly reveal the dynamic coupling between different frequencies in the phase sequence, can more intuitively study the admittance characteristics of the grid-connected inverter based on the PLL structure, and further proposes an optimization control method of the phase-locked loop to improve the stability of the PLL synchronization control under the condition of a weak grid.

The invention discloses a network construction type PCS test power supply, which comprises an impedance network superposition module and a main power distribution module, and is characterized in that the impedance network superposition module comprises a waveform injection unit, and the main power distribution module comprises a circuit breaker and a plurality of contactors; each phase of the power grid or the power grid simulator is connected with each phase of the grid-forming type energy storage converter through a circuit breaker and a plurality of contactors in sequence, and each phase of one contactor is connected with a waveform injection unit in parallel; by controlling the start and stop of the waveform injection units connected with each phase and outputting voltages with different frequencies and amplitudes, the harmonic wave, oscillation and impedance change conditions of each phase of a power grid are simulated, and the grid-forming type energy storage converter is tested. The method has the advantages that accurate simulation of power grid characteristics and flexible adaptation to different test scenes are realized.

The invention discloses a bidirectional Gamma-Z source solid-state circuit breaker parameter design method based on a time domain. The method comprises the following steps of: 1, establishing a function relationship among power supply voltage, output current, load resistance, fault resistance, equivalent output resistance and coupling inductance value; 2, solving an analytical expression of the output current; 3, deriving an expression of current reflected to the thyristor and an analytical expression of current flowing through the thyristor; 4, calculating the current zero-crossing time of the thyristor and the output current at the moment; 5, deriving an expression of voltages at the two ends of the thyristor, and calculating the time when the thyristor bears the reverse bias voltage; step 6, deriving a capacitance value analytical expression of the capacitor in an ideal short circuit state; and step 7, determining impedance network parameters based on an optimal design target.

The invention relates to the technical field of relay protection, in particular to a distance protection method and device based on transient state identification of a converter and a medium, and aims to realize extraction of fault transient data of a converter grid-connected system under different small time windows by utilizing a fast vector extraction algorithm, and realize distance protection of the converter grid-connected system by utilizing extracted electrical quantities under the different small time windows. And constructing a plurality of groups of irrelevant fault loop equations. The characteristics that a zero-sequence impedance network does not change along with the regulation and control characteristics of a current converter and positive and negative sequence equivalent impedance fluctuates along with the regulation and control characteristics of the current converter in an asymmetric grounding fault scene are utilized, the zero-sequence electrical quantity, opposite-end system parameters and transition resistance in an equation are eliminated, and a linear equation only containing one unknown quantity of the fault distance is constructed and rapidly solved. A direction element, a phase selection element and the distance protection principle are combined, and the distance protection device suitable for the converter access system is provided. The problem that a traditional distance protection algorithm is easily influenced by transition resistance and opposite end system parameters in a converter access system can be effectively solved.

The application discloses a desktop card dispenser based on an RFID chip and relates to the field of radio frequency identification technology. The application compares a pre-stored protocol feature library with a preamble bit segment, automatically identifies EPC / Guobiao label protocol types, and exempts from manual sorting operation. In combination with a first-different-later-same strategy of a composite handshake instruction sequence, protocol camouflage handshake is completed within a preset time window, multi-protocol conversion delay is significantly shortened, and label response timeout failure is avoided. A TID grouping processing module divides operation batches according to a predetermined bit position of a unique label code, executes a protocol camouflage process on different grouping labels in sequence, isolates response time sequences from a physical layer, and reduces signal collision probability in a dense label scene. When the number of labels exceeds a set threshold, the grouping mechanism is automatically enabled, so that the stability of batch card dispensing operation is ensured. A tunable pi-type impedance network dynamically optimizes an antenna standing wave ratio according to label distance, and expands an effective reading and writing range.

The invention discloses a fully differential negative impedance phase shifter circuit which comprises an input network, an operational amplifier and a feedback network. The input network comprises two differential signal input ends, an equivalent negative impedance network is formed through cross coupling connection of a resistor and a capacitor, and two paths of differential input signals are respectively transmitted to the negative input end and the positive input end of the operational amplifier; the operational amplifier is used for receiving the differential signal processed by the input network and driving to generate a differential output signal; the feedback network is in bridge connection with feedback branches in which resistors and capacitors are connected in parallel between the positive phase output end and the negative input end of the operational amplifier and between the negative phase output end and the positive input end of the operational amplifier. According to the fully-differential negative impedance phase shifter circuit, a negative impedance mechanism is adopted, and wide-range and high-stability phase shifting under a fully-differential framework is achieved through cross coupling connection between the resistor and the capacitor and the input port of the fully-differential operational amplifier.

The embodiment of the invention provides a self-adaptive impedance adjustment voltage sampling circuit and an electronic chip. The self-adaptive impedance adjustment voltage sampling circuit comprises a first control circuit, a second control circuit, a first switch module, a second switch module and a comparison circuit, whether the sampling impedance network of the ADC sampling circuit is matched or not is judged by obtaining the relation between the absolute value of the difference value of the first sampling voltage and the second sampling voltage of the sampling node before and after the adjusting resistor is input and the preset threshold value. According to the collected sampling voltage of the sampling node in the previous sampling period and the sampling voltage of the sampling node in the current sampling period, whether the input voltage of the input node is increased or decreased is determined, and then according to the determined working condition of the input voltage of the input node, in the sampling period of voltage sampling, the working condition of the input node is determined. Accurate sampling voltage of the sampling node is output, and the accuracy of the output sampling voltage of the sampling node is ensured on the premise that the sampling impedance network matching of the ADC sampling circuit is ensured.

The utility model provides an attenuator testing device, which is used for solving the technical problem of screening the impedance of an attenuator. The attenuator testing device comprises a tool body, an impedance matching assembly and a first wire group, the tool body is provided with an installation interface, and the installation interface is configured to be electrically connected with a first port, a second port and a grounding port of a to-be-tested attenuator when the to-be-tested attenuator is installed on the installation interface. The impedance matching assembly is installed on the tool body and electrically connected with the installation interface, the impedance matching assembly is electrically connected with the first port and the grounding port of the to-be-tested attenuator through the installation interface to form a to-be-tested impedance network, and the impedance of the impedance matching assembly is equivalent to the characteristic impedance of the to-be-tested attenuator. The first end of the first wire group is electrically connected with the installation interface, the first end of the first wire group is electrically connected with the second port and the grounding port of the attenuator to be detected through the installation interface, the second end of the first wire group is electrically connected with the detection equipment, and the detection equipment detects the actual impedance of the impedance network to be detected.

The invention discloses a multi-target broadband oscillation active defense controller for a multi-infeed system of a new energy power station. The multi-target broadband oscillation active defense controller is composed of a broadband oscillation risk sensor based on an impedance network model and a multi-target controller. The risk sensor samples key time domain working point information of each new energy power station multi-infeed system through communication, and obtains oscillation risk information under the stable operation condition of the system by using an impedance network model of the new energy power station multi-infeed system; the multi-target controller is a deep neural network obtained by deep reinforcement learning and training under the guidance of perceived oscillation risk information; the multi-target controller outputs a multi-target broadband oscillation active defense control action through forward propagation; and the active defense control action is issued to the converter in each new energy power station through communication, and is used for adjusting the working state of each converter to realize active defense control on the broadband oscillation risk. According to the invention, beforehand active defense control of broadband oscillation of the multi-infeed system is realized.

The present application relates to the technical field of radio frequency power supply, in particular to a power supply system and a matching method suitable for multi-stage pulse, the power supply system comprises: a radio frequency power supply, outputting multi-stage pulse; a matching network, comprising a mechanical variable capacitor and a switch capacitor array, connected between the radio frequency power supply and a load, the present application matches the multi-stage pulse by mixing the impedance network and the frequency of the radio frequency power supply, so as to achieve the purpose of quickly matching the multi-stage pulse, meanwhile, by using the idea of segmented matching, the first stage pulse of the multi-stage pulse is matched in impedance by the mechanical variable capacitor and the frequency of the radio frequency power supply, in the subsequent pulse, the capacitance value of the mechanical variable capacitor is kept unchanged, and the impedance is matched by the switch capacitor array and the frequency of the radio frequency power supply, so as to realize the fast and accurate impedance matching in the complex multi-stage pulse process, and ensure that the radio frequency energy is transmitted to the load efficiently and stably.

The present disclosure provides a driving circuit and a semiconductor memory, a control end of a first control unit receives a first driving signal, a first end is connected to a first power supply end, a second end is connected to a first end of a first impedance network, a control end of the first impedance network receives a first original correction signal, and a second end is connected to an input / output end. The first control unit controls whether a transistor in the first impedance network is turned on to the first power supply end, the first impedance network controls the state of the transistor in the first impedance network based on the first original correction signal to correct the resistance value of the first impedance network, and the first control unit controls the transistor in the first impedance network to be turned on to the first power supply end under the control of the first driving signal, and when the transistor in the first impedance network is controlled by the first control unit to be turned off under the control of the first original correction signal, the transistor in the first impedance network is in a cut-off state from the input / output end, thereby being able to reduce the capacitance on the input / output end and improve the data transmission quality.

This invention relates to the field of photovoltaic energy storage technology, specifically to a method for configuring the energy storage capacity of a photovoltaic energy storage system. It includes modules for parameter construction, thermal intrusion simulation, coupled solution, and capacity iteration. The system establishes a heat flux intrusion model by acquiring environmental meteorological and battery electrochemical parameters. Its core is the construction of a thermo-electrochemical coupling impedance network, using external heat flow as an interference field to solve for the dynamic thermal equilibrium capacity boundary under core temperature constraints. Based on this, the battery module is iteratively corrected according to load requirements. This invention achieves deep coupling between the thermophysical environment and electrochemical performance, accurately quantifying the dynamic impact of thermal stress on capacity and avoiding inflated capacity configurations.

The invention provides a power conversion device and a control method. The power conversion device comprises a first bridge circuit, an impedance network, a transformer, a second bridge circuit and a control device, the control device is connected with a plurality of switching tubes in the first bridge circuit and the second bridge circuit, and the control device is configured as follows: when the power needing to be output by the power conversion device is first power, the impedance network is connected with the first bridge circuit; controlling the plurality of switch tubes based on a pulse cross-period modulation mode, and performing phase shift control and frequency modulation control on the plurality of switch tubes based on a first control parameter at least in a steady-state time period in a wave sending time period corresponding to the pulse cross-period modulation mode; wherein the first control parameter is a control parameter for performing phase shift control and frequency modulation control on the plurality of switching tubes under the reference power, the reference power is smaller than or equal to the power point with the highest energy conversion efficiency, and the first power is smaller than the reference power.

This invention discloses a power coordination method for preventing overmodulation in grid-connected quasi-Z-source inverters with integrated photovoltaic and energy storage systems, addressing photovoltaic power fluctuations. The method involves collecting photovoltaic voltage, photovoltaic current, and battery voltage to calculate the available photovoltaic power and constructing a feasible active power boundary based on the DC-side energy balance relationship of the quasi-Z-source impedance network. When the original virtual synchronous generator active power reference value exceeds this feasible boundary, the method calculates the power derating online and corrects the active power reference value, keeping the inverter operating point within the linear modulation region. This invention eliminates the need for additional battery current closed-loop or quasi-Z-source network voltage-current closed-loop; overmodulation prevention under photovoltaic power fluctuations is achieved solely through supervisory layer power reference correction. It is suitable for applications involving the retrofitting of existing photovoltaic power plants into grid-connected photovoltaic-energy storage systems.

This invention discloses an ultrasonic power supply impedance network, a variable inductor, a control circuit, and a control method, including a variable inductor, an ultrasonic power supply impedance network, and a control circuit. The variable inductor consists of a main magnetic core, two auxiliary magnetic cores, a main winding, and auxiliary windings, with an air gap between the auxiliary magnetic cores and the main magnetic core. By adjusting the control current, the magnetic saturation level of the auxiliary magnetic cores is changed, thereby changing the magnetic saturation state of the main magnetic core, achieving dynamic change of the inductance value. The ultrasonic power supply load is capacitive, and the control circuit can make the load impedance and the variable inductor reach a resonant state, effectively reducing losses and improving energy transmission efficiency. Furthermore, the impedance matching method of this invention utilizes two auxiliary inductors, improving the impedance matching speed through coarse adjustment and improving the impedance matching accuracy through fine adjustment. It has advantages such as high matching accuracy, wide matching range, and dynamic adjustment, further expanding the application field of variable inductors.

This invention belongs to the field of power system automation technology, specifically relating to a reactive power and voltage balancing coordination control system for wind farms that suppresses circulating currents within the wind farm, aiming to solve the problems of reactive power circulating currents and voltage unevenness within wind farms. The system includes: a multi-dimensional parameter real-time sensing unit, an impedance network dynamic reconstruction unit, a circulating current potential energy assessment unit, a voltage balancing coordination calculation unit, a virtual impedance compensation control unit, and a high-speed coordinated command distribution unit. By identifying impedance online and constructing a dynamic network model, the system calculates the potential difference to extract circulating current indicators and solves for reactive power output correction values ​​under multiple constraints, utilizing virtual impedance technology to offset physical impedance differences. This application achieves proactive intervention and precise suppression of circulating currents within the wind farm, effectively reducing network losses and improving voltage support capabilities, ensuring the efficient and stable operation of the wind farm.

This application discloses an impedance network and a low-noise amplifier. The impedance network includes a first inductor unit, a second inductor unit, and a switching unit. A first end of the first inductor unit serves as the first end of the impedance network, and a second end is connected to both the first end of the second inductor unit and the first end of the switching unit. A second end of the second inductor unit serves as the second end of the impedance network and is connected to the second end of the first switching unit. When the switching unit is off, it introduces parasitic capacitance, forming a high-impedance resonant network with the parallel-connected second inductor unit. When the switching unit is on, it short-circuits the second inductor unit, and the first inductor unit, along with other capacitors, forms a low-impedance resonant network. This application can improve the utilization rate of each component in the impedance network, avoiding the need to set up a separate impedance network for each frequency band. Instead, it directly switches to the impedance network required for different frequency bands, thereby reducing the number of impedance network components and the occupied area, and lowering the cost of the corresponding low-noise amplifier.