407 results about "Input impedance" patented technology

The invention discloses a column type distribution transformer winding abnormity detection system and detection method. The detection system comprises a frequency response detection instrument, a signal coupling assembly, an impedance matching module and a data processing module. The frequency response detection instrument is used for outputting a frequency sweep excitation signal and collecting a winding response signal; the signal coupling assembly is used for isolating power frequency voltage and filtering low-frequency interference; the impedance matching module is used for adjusting output impedance and input impedance to realize matching with electrical characteristics of different windings; and the data processing module is used for constructing an equivalent detection loop model, completing frequency response simulation calculation and carrying out frequency domain analysis and anomaly identification on an actually measured response curve. According to the invention, electrified state diagnosis of distribution transformer winding structure abnormity (such as deformation and loosening) can be realized.

The invention discloses a sensor array acquisition system for detecting gas, and relates to the field of gas sensors. The sensor array acquisition system for detecting gas comprises a gas sensor array, a signal conditioning circuit, an analog-to-digital conversion module, a control module and a power supply module. According to the sensor array acquisition system for detecting the gas, the voltage follower circuit with high input impedance is adopted, so that the problem of attenuation during signal acquisition of a high-impedance sensor is effectively solved, and the signal acquisition precision is improved. Through the adjustable direct-current bias circuit and the differential amplification circuit, the dynamic adjustment of the measurement range is realized, the gas detection requirements of different concentration ranges can be met, and hardware does not need to be replaced. A constant-current driving chip is adopted to control a sensor heating circuit, heating current can be accurately set by adjusting external resistance, it is ensured that the sensor works at the optimal temperature, and the stability and response speed of the sensor are improved.

The invention discloses a cable high-frequency impedance characteristic analysis method based on bipolar trapezoidal wave excitation, and belongs to the technical field of power equipment state monitoring and fault diagnosis. In order to solve the problems of low test efficiency, insufficient high-frequency parameter modeling precision and weak anti-interference capability in cable high-frequency impedance characteristic analysis of a traditional sine wave excitation method, the method comprises the following steps: generating an odd-symmetry bipolar trapezoidal wave excitation signal with specific frequency and amplitude, and injecting the signal into the head end of a cable to be tested through a coupling device after power amplification; synchronously acquiring a high-frequency response signal of the key position of the cable under the excitation of the bipolar trapezoidal wave by using a data acquisition system; preprocessing the high-frequency response signal, converting the high-frequency response signal into a frequency domain through Fourier transform, calculating input impedance of the cable under different harmonic frequencies, and synthesizing a broadband impedance spectrum; based on the broadband impedance spectrum, the amplitude-frequency characteristic and the phase-frequency characteristic of impedance are analyzed, and cable state evaluation, partial discharge detection, insulation defect diagnosis or fault point positioning are realized. The method is used for an electric power system.

The present application discloses a low-cost and high-performance radio-frequency amplifier, comprising an input stage circuit, a common-gate stage circuit, and an output load circuit. The input stage circuit implements conversion from a single-ended signal to a differential signal, implements input impedance matching, and converts an inputted radio-frequency voltage signal into a radio-frequency current signal. The input stage circuit comprises a first three-coil transformer, consisting of a primary coil, a secondary coil, and a third coil. The common-gate stage circuit transmits the radio-frequency current signal outputted by the input stage circuit to the output load circuit, increases the withstand voltage and equivalent output impedance of the circuit, and implements gain control in at least two modes. The output load circuit converts the radio-frequency current signal from the common-gate stage circuit into a radio-frequency voltage signal, implements conversion from a differential signal to a single-ended signal, and outputs an amplified radio-frequency voltage signal. The present application provides a radio-frequency amplifier having a small size, broadband matching, high linearity, a large dynamic range, and low design complexity.

The utility model provides a sampling circuit, an analog circuit and electronic equipment, and the sampling circuit comprises an input processing unit which is connected with the output end of a target circuit, and is used for collecting the common-mode output voltage of the target circuit, and carrying out the sampling input processing of the common-mode output voltage, and obtaining a first operational amplifier in-phase sampling signal and a first operational amplifier anti-phase sampling signal; the signal amplification unit is connected with the input processing unit and is used for respectively amplifying the first operational amplifier in-phase sampling signal and the first operational amplifier anti-phase sampling signal to obtain a second operational amplifier in-phase sampling signal and a second operational amplifier anti-phase sampling signal; and the signal stabilization unit is connected with the signal amplification unit and the control circuit, and is used for keeping the second operational amplifier in-phase sampling signal and the second operational amplifier anti-phase sampling signal, generating a feedback signal according to the second operational amplifier in-phase sampling signal and the second operational amplifier anti-phase sampling signal, and outputting the feedback signal to the control circuit. In this way, the input impedance and the sampling precision are improved.

The invention discloses an AFE analog front-end circuit applied to a multi-channel high-speed optical receiver. The circuit comprises an SF-TIA, a single-ended to differential circuit and a CLTE. The SF-TIA, the single-ended to differential circuit and the CLTE are connected in sequence; the SF-TIA is used for converting an input current signal into a voltage signal and transmitting the voltage signal to the single-ended to differential circuit; wherein the current signal is obtained by converting an input optical signal; the single-ended to differential circuit is used for converting the voltage signal into a differential voltage signal and transmitting the differential voltage signal to the CLTE; and the CLTE is used for compensating the high-frequency gain of the differential voltage signal to obtain a compensated voltage signal and outputting the compensated voltage signal. The amplifier has the advantages of being high in gain, low in power consumption, low in input impedance, low in noise, low in requirement for power supply voltage and simple in structure.

A method can include wireless circuits that, by operation of transmit switch circuits, include a transmit component in an output signal path between a transmit amplifier and an antenna port, the output signal path including a shared matching network. By operation of a transmit amplifier, an output signal can be generated for transmission over an output signal path to an antenna port. In a receive mode, by operation of the transmit switch circuits, an input impedance of the transmit component can be excluded from an input signal path between the antenna path and a receive amplifier. An input signal path can include the shared matching network. By operation of the receive amplifier, amplifying the received input signal. Corresponding devices and systems are also disclosed.

The invention discloses a phased-array antenna control method and system based on impedance matching, a medium and a product, and relates to the technical field of antennas. In the method, before the phased-array antenna works, a target impedance matching parameter is calculated for active input impedance under each preset scanning angle point; establishing a target mapping relation table based on the plurality of preset scanning angle points and the corresponding target impedance matching parameters; during the working period of the phased-array antenna, receiving a target scanning angle, and calculating to obtain a corresponding beam pointing phase value for each antenna unit in the antenna array according to the target scanning angle; determining a real-time impedance matching parameter based on the target scanning angle and the target mapping relation table; and loading the beam pointing phase value to a phase shifter in the feed network, and applying a real-time impedance matching parameter to the dynamic impedance matching network, so that the input impedance of the antenna array is matched with the characteristic impedance of the feed network. By implementing the technical scheme provided by the invention, the radio frequency performance of the phased-array antenna is improved.

A DFIG wind power facility configured to be operated during grid faults is provided. The wind power facility includes a Doubly-Fed Induction Generator, a control system, an electric converter, a short-circuit controlled switch to selectively short-circuit the stator and a Stator Neutral Brake Chopper coupled to the stator. The DFIG includes a rotor and a stator, the stator including at least one three-phase winding. The electric converter includes a Machine Side Converter, a Grid Side Converter and a DC link connected therebetween. The SNBC includes a three-phase rectifier including three inputs, an impedance and an active high-frequency switch configured to vary the average value of the impedance by adjusting its duty cycle; each of the three inputs of the rectifier is connected to a phase of the at least one three-phase winding of the stator. Methods for operating a DFIG wind power facility during grid faults are also provided.

The invention provides a gain-reconfigurable active phase shifter with a low phase error, and relates to the technical field of phase shifters, and the phase shifter comprises a quadrature coupler which converts a radio frequency input signal into a shunt radio frequency signal; the input matching Balun converts the shunt radio frequency signal into a shunt differential signal; the digital control signal received by the phase inversion variable gain amplifier is used for controlling the on-off state of a differential pair in each differential group, and determining a differential combination current corresponding to a differential pair combination in a conduction state based on a shunt differential signal corresponding to each differential pair; the differential combination current is used for representing a gain state corresponding to the differential pair combination; the input impedance and the output impedance of the phase inversion variable gain amplifier in different gain states are kept unchanged; the vector synthesis module determines a phase shift differential signal based on the differential combined current; the output matching Balun converts the phase shift differential signal into a radio frequency output signal. The antenna has a wide gain adjustable range and a low phase error.

A power converter includes switching section, tuning section, and rectification section. The tuning section includes transformer with a primary inductance and a secondary inductance and a primary series capacitor connected in series with a primary winding and a secondary series capacitor connected in series with a secondary winding. The primary series capacitor is selected with a resonant frequency with the primary inductance and the secondary series capacitor is selected with the resonant frequency with the secondary inductance. The tuning section includes a resonant tank with a primary parallel capacitor connected in parallel with the primary series capacitor and the primary winding and a primary resonant inductor connected between the switching section and a connection to the primary parallel capacitor. An input impedance of the resonant tank at a switching frequency is below a frequency intersecting an open circuit input impedance and a short circuit input impedance of the resonant tank.

The invention is suitable for the technical field of radio frequency front ends, and particularly relates to a low-noise amplifier and a radio frequency chip. The low-noise amplifier provided by the invention comprises an input switching circuit, an amplifying circuit and an output matching circuit which are electrically connected in sequence, the input switching circuit comprises a plurality of input matching units, and the plurality of input matching units are used for receiving radio frequency signals of different frequency bands respectively; the amplifying circuit comprises a first amplifying unit, a first inductor and a plurality of second amplifying units connected in parallel, the input ends of the second amplifying units serve as the input end of the amplifying circuit, and the input ends of the second amplifying units are connected with the output ends of the input matching units in a one-to-one correspondence mode. Compared with the prior art, the low-noise amplifier disclosed by the invention can be used for independently optimizing the input impedance of each input port, so that not only can the noise coefficient be optimized, but also the optimal gain and linearity performance can be obtained.

This invention relates to the field of pulse circuit technology and discloses a high-efficiency AC power line zero-crossing detection chip, including a path selection module, a signal processing module, and a driving module. The path selection module switches the charging circuit according to the potential of the internal power supply capacitor. The signal processing module uses a feedback loop to adjust the switching level of the sampling branch and generate a zero-crossing trigger pulse signal. The driving module responds to the zero-crossing trigger pulse signal by segmentally turning on the internal power supply capacitor and the external energy supply capacitor in the initial and subsequent stages of the zero-crossing point. This invention solves the contradiction between the ultra-high input impedance sampling environment and the driving strength through a controlled hysteresis window and a segmented current injection mechanism, suppresses signal jitter, improves the timing accuracy of zero-crossing detection, and effectively reduces the static power consumption of the system.

The present application relates to a kind of broadband impedance spectrum cable fault identification method, system and storage medium, comprising: according to any preset cable fault type, establish cable equivalent model;Frequency-sweep signal is input to model, obtain the parameter of cable core, sheath and steel armor under different frequency-sweep signals, and the input impedance of cable head under different frequency-sweep signals is calculated based on cable modulus matrix and input impedance formula, draw fault broadband impedance amplitude spectrum and phase spectrum;Repeat the above steps, obtain cable fault broadband impedance amplitude spectrum and phase spectrum;Real-time acquisition actual cable input impedance and draw real-time broadband impedance amplitude spectrum and phase spectrum, compare with cable fault broadband impedance amplitude spectrum and phase spectrum, identify cable fault type and fault point distance from head end.Compared with prior art, the present application realizes the quick cable fault identification and fault point determination.

A Doherty amplifier according to the present disclosure comprises a main amplifier, an auxiliary amplifier, a distribution circuit that distributes signals to the main amplifier and the auxiliary amplifier, and a phase compensation circuit. The main amplifier has a first input matching circuit and a plurality of main amplification stages. The auxiliary amplifier has a second input matching circuit and a plurality of auxiliary amplification stages. The distribution circuit has a first line connected to the first input matching circuit and a second line connected to the second input matching circuit. The electrical length of the first line is such that the input impedance of the first line is higher than the characteristic impedance of the first line and the imaginary component is less than 10% of the real component when a small signal is input. The electrical length of the second line is such that the input impedance of the second line is higher than the characteristic impedance of the second line and the imaginary component is less than 10% of the real component when a small signal is input. The phase compensation circuit is provided in an inter-stage matching circuit of the plurality of main amplification stages or the plurality of auxiliary amplification stages.

The invention discloses a high-frequency electrotome negative plate impedance detection method and system and a high-frequency electrotome, and the detection method comprises the steps: an impedance detection signal preprocessing step: determining an acquisition time interval of an impedance detection signal according to a current working mode and a corresponding optimal acquisition time interval; only the impedance detection signals in the acquisition time interval are collected; the acquisition time interval is one or more carrier periods in which the signal-to-noise ratio of the impedance detection signal is higher than the average value of the signal-to-noise ratio in a unit modulation period T under the current working mode; and the optimized impedance detection signal is filtered and amplified and then is input into an impedance calculation module to calculate and obtain a real-time impedance value of the negative plate of the high-frequency electrotome. Interference is filtered out by monitoring information such as power and impedance intervals when the high-frequency electrotome works and combining noise waveform characteristics of different working modes.

The application discloses a kind of adjustable low-pass filter circuits based on self-bias pseudo resistance, the filter circuit includes: self-bias pseudo resistance circuit, differential source follower circuit and gain compensation circuit.The self-bias pseudo resistance circuit is made of back-to-back PMOS transistor, and its gate-source voltage is controlled by the direct current component of system input signal and output signal, so as to realize the function of adjustable large resistance;The differential source follower circuit uses common-drain amplifier, and converts passive amplifier into active amplifier with large input impedance and medium output impedance, while providing stable adjustable bias for the above-mentioned pseudo resistance;The gain compensation circuit is used to compensate for the gain loss of the common-drain amplifier due to the substrate effect.The low-pass filter circuit of the application can achieve considerable time constant with very small chip area and power consumption, and can be used in wearable physiological signal detection device, with the advantages of low power consumption, small area, high stability and the like.

The application provides a design method of a broadband multi-modal vibration suppression damping material based on fractal geometry, comprising: constructing an initial geometric configuration of the damping material, the damping material being composed of a periodic arrangement of a three-dimensional unit cell structure in a plane; layering the unit cell structure to construct a parameterized model of the unit cell structure by using a fractal dimension of the unit cell structure and layer structure parameters; constructing a vibration impedance transfer equation according to the parameterized model of the unit cell structure, determining input impedances of the innermost layer and the outermost layer, and determining vibration attenuation amounts of the unit cell structure in multi-target frequency bands by using the input impedances of the innermost layer and the outermost layer; and optimizing the configuration and the parameterized model of the unit cell structure until the vibration attenuation amounts of the unit cell structure in the multi-target frequency bands meet load platform requirements. The broadband multi-modal vibration suppression damping material based on fractal geometry constructed can realize efficient dissipation of 10-1000 Hz broadband vibration energy and solve the frequency selectivity limitation of traditional homogeneous damping materials in multi-frequency vibration suppression.

A device comprises an input stage, a signal distribution network comprising a plurality of passive elements, and a plurality of output stages coupled to the signal distribution network. The input stage is configured to drive a signal onto the signal distribution network. The signal distribution network is configured to distribute the signal to the plurality of output stages. Each output stage of the plurality of output stages comprises a variable resistance element and a variable reactance element, for tuning a complex input impedance of the output stage to obtain a signal transfer characteristic for transferring the signal from the input stage to the output stage over the signal distribution network.

The utility model discloses a charging and downloading integrated cabinet and a seismic exploration system, and belongs to the field of seismic exploration. The charging and downloading integrated cabinet comprises a signal source assembly and a plurality of interface circuit boards. Each interface circuit board is provided with a voltage following circuit, and the voltage following circuits are connected between the signal interface end of the signal source assembly and the seismic exploration node instrument. The voltage follower circuit has the characteristics of high input impedance and low output impedance, so that under the action of the voltage follower circuit, the acquisition test signal sent by the signal source assembly can be normally transmitted to the seismic exploration node instrument through the voltage follower circuit; in addition, it can be ensured that the abnormal voltage of the circuit station does not affect the signal source assembly, so that the signal source assembly can send a normal acquisition test signal to perform acquisition index test on other normal seismic exploration node instruments.

The invention particularly relates to an active integrated antenna which comprises at least two antenna units, and each antenna unit comprises a feeder line structure used for being connected with one path of power amplifier output of a Doherty power amplifier and an antenna radiation unit connected with the feeder line structure. By adjusting the structural parameters of each antenna unit, the input impedance of each antenna unit is matched with the power amplifier output impedance of the corresponding path. The invention designs a multifunctional antenna array integrating radiation, impedance conversion and power synthesis, and the multifunctional antenna array is used for directly replacing an indispensable output matching network and a power synthesis network in a traditional Doherty power amplifier. According to the Doherty power amplifier integrated antenna, an output matching network and a power synthesis network which are necessary in a traditional Doherty power amplifier integrated antenna are eliminated, the problem that significant loss is introduced by adopting the matching network in the prior art is fundamentally avoided, and the efficiency of the Doherty power amplifier is effectively improved.

This invention provides an output impedance calculation device, which includes: a control unit, an adjustment unit, a LORA transmitting unit, a first impedance calculation unit, a second impedance calculation unit, a matching unit, and a transmitting antenna. The control unit is used to transmit wireless signals; the LORA transmitting unit is used to convert wireless signals into LORA signals; the first impedance calculation unit is used to calculate the input impedance based on the LORA signals; the second impedance calculation unit is used to calculate the output impedance based on the LORA signals; the control unit is used to calculate the reflection coefficient based on the input and output impedances, and to calculate the standing wave ratio based on the transmission coefficient; the adjustment unit is used to adjust the impedance in the circuit based on the standing wave ratio and the reflection coefficient, thereby achieving impedance matching and balance between the input and output terminals of the line, improving the output quality of radio signals, reducing the overall output power consumption, and reducing harmonic interference.

The invention discloses a DC micro-grid power buffer safety control method and device aiming at FDI attack, and relates to the technical field of power electronics and power system control. The method comprises the steps of obtaining a block matrix of a DCmGs system node current equation according to the Kirchhoff's current law; adopting Kron simplification to eliminate internal node voltage, obtaining a relation between a port current vector and a voltage vector, and constructing a small signal model of the port voltage vector; based on a small signal model, a linear mapping relation about disturbance of bus voltage to equivalent input impedance of each power buffer is constructed, modeling and linearization are carried out on energy and adjustable input impedance of each power buffer, a network coupling small signal model is constructed, and a second-order high-gain observer is designed; and if the FDI attack exists in the DCmGs system, an anti-FDI attack elastic control law is designed, so that the closed-loop voltage in the DCmGs system and the energy of a power buffer are quickly converged, and buffeting is inhibited. By adopting the method, the DCmGs system can be prevented from buffeting in an unknown FDI attack scene.

Provided are an impedance matching circuit and method, a radio frequency circuit, and an electronic device, and belong to the technical field of electronics. The impedance matching circuit comprises a transducer, a first adjustable circuit and a first switch circuit coupled between a first coil of the transducer and a first signal end, a second adjustable circuit and a second switch circuit coupled between a second coil of the transducer and a second signal end, and a control circuit coupled with the adjustable circuits and the switch circuits. The control circuit can adjust the working parameters of the adjustable circuits and the on-off states of the switch circuits based on the input impedance and the output impedance determined under different signal gain configurations, so as to achieve impedance matching. Therefore, the impedance matching circuit can achieve better impedance matching for different signal gain configurations, and has better flexibility in impedance matching.

The application discloses a tracking lock type maximum power point tracking circuit and an implementation method thereof, which comprises a rectifier circuit, a control circuit, a step-down-step-up converter control circuit and a step-down-step-up converter. The rectifier circuit is used for converting input alternating current energy into direct current energy. The control circuit is used for judging the length of current inductance demagnetization time, adjusting the current inductance demagnetization time, realizing indirect detection of inductance current zero-crossing point, and generating a switch timing control signal. The step-down-step-up converter control circuit is used for generating a first switch tube driving signal and a second switch tube driving signal. The step-down-step-up converter is used for adjusting input impedance according to the first switch tube driving signal and the second switch tube driving signal, and realizing maximum power point tracking. The application can realize adaptive locking of the maximum power point under different vibration frequencies and different open circuit voltages, improve the tracking speed of the circuit when the input changes, and can be widely applied to the technical field of integrated circuits.

The invention discloses a double-side impedance trajectory optimization high-frequency wireless electric energy transmission system and method based on multi-mode matching network integration and a near-zero impedance angle rectifier, and relates to the field of high-frequency wireless electric energy transmission. The problems that the impedance conversion function of an existing high-frequency resonant rectifier structure shows nonlinear capacitive change, a large number of reactive components are generated, the impedance angle fluctuates greatly along with the load, the voltage stress is high, the efficiency is sharply reduced in the wide load range and the like are solved. One end of a multi-mode matching network is connected with a Class-E power amplifier and the other end of the multi-mode matching network is connected with a coupling coil through impedance track optimization at a primary side, so that output power change compression under wide-range load change is realized; the secondary side is connected with the coupling coil through a near-zero impedance angle rectifier, the near-zero impedance angle rectifier comprises a three-unit novel resonant rectifier, the three-unit novel resonant rectifier comprises three-mode smooth input impedance, the three-mode smooth impedance is connected in parallel, and impedance angle compression and high-efficiency operation under a wide load are achieved.

This invention discloses a millimeter-wave broadband high harmonic suppression tripler, comprising an input matching network, a time-domain shaping tripler unit, and a differential common-source output stage. The proposed time-domain shaping tripler unit employs transistor pairs with different gate widths and bias voltages to superimpose two sets of voltage signals of different amplitudes in the time domain, thereby enhancing the inherent harmonic suppression of the tripler unit. Furthermore, by connecting a common-mode impedance control in series at the center tap of the primary inductor coil of the output transformer of the tripler unit, the output power of the third harmonic is further improved. The input matching network achieves single-ended to differential conversion, with its primary and secondary coil center taps grounded and open-circuited respectively in a counterintuitive manner, improving differential-mode balance and common-mode stability. Simultaneously, by using a series-coupled inductor, the quality factor of the transistor input impedance is reduced, improving the bandwidth performance of the tripler.

The invention discloses an ultra-wideband small radio frequency antenna for PE pipe detection, and relates to the technical field of antennas. The antenna comprises an insulating medium substrate and a radiation structure arranged on the front surface of the insulating medium substrate. The radiation structure comprises a main radiation patch formed by an index gradual change slot line, an annular patch arranged at an interval with the tail end of the main radiation patch, and a strip-shaped patch arranged at an interval with the annular patch. The resistor element comprises a first resistor, a second resistor and a third resistor, and the main radiation patch is connected with the annular patch through the first resistor; a radiation part of the antenna forms a specific resistance loading network through a radiation structure and a resistance element, and a slot line feed structure feeds energy, so that resonance with lower frequency can be effectively excited, and the low-frequency cut-off frequency of the antenna is reduced, which is crucial for detecting a deep target; therefore, the input impedance of the antenna is very stable in the whole ultra-wideband, the energy transmission efficiency is ensured, and the gain and efficiency of the antenna are gradually increased.

The invention discloses an antenna tuning matching network circuit of a mobile platform short wave shunt-fed antenna and a tuning method of the antenna tuning matching network circuit. The circuit comprises a series inductor L1, a series capacitor C2, a parallel inductor L2 and a parallel capacitor C1, one end of the series inductor L1 is connected with one end of a shunt-fed antenna, the other end of the series inductor L1 is connected with one end of the series capacitor C2, and the other end of the series capacitor C2 is connected with one end of a power amplifier; the common end of the series inductor L1 and the series capacitor C2 is connected to one end of the parallel inductor L2 and one end of the parallel capacitor C1. The other end of the shunt inductor L2 is connected with the other end of the shunt capacitor C1, and the common end is connected to the other end of the shunt-fed antenna and the other end of the power amplifier. According to the input impedance admittance data of the mobile platform short-wave shunt-fed antenna, tuning is carried out in multiple frequency band ranges. According to the invention, perfect matching of the short-wave shunt-fed antenna which shows strong capacitance in a high frequency band and even has a second resonance point is realized, so that the tuning capability of the antenna tuner is improved, and the communication effect is improved.

The invention discloses a low noise amplifier and a wireless receiving system. The low-noise amplifier comprises an input matching circuit used for receiving a to-be-amplified signal output by a signal input end and matching impedance between the signal input end and an input end of a first amplifying circuit; the first amplification circuit is used for performing first-stage amplification processing on the signal to be amplified; the inter-stage matching circuit is used for matching the output impedance of the amplifying circuit with the input impedance of a second amplifying circuit; the second amplification circuit is used for performing second-stage amplification on the output signal of the inter-stage matching circuit; the output matching circuit is used for matching the output impedance of the second amplifying circuit with the impedance between a signal output end and outputting an amplified signal through the signal output end; and the bias adjusting circuit is used for adjusting the bias voltage of at least one of the first amplifying circuit and the second amplifying circuit. By adopting the scheme, the dynamic range of the low-noise amplifier can be improved.