5281 results about "Operational amplifier" patented technology

The invention discloses a high-precision current detection circuit calibration system, and belongs to the technical field of current detection circuit calibration. Comprising a shunt resistor, a Hall sensor array, a chopping amplifier, a low-noise operational amplifier, a temperature sensor, an ADC acquisition unit, an RC low-pass filter, a signal conditioning unit, a main control unit, an environmental parameter adaptive compensation module and a gain adaptive adjustment module. After an original signal is obtained from a multi-channel sensor, a dynamic error model is constructed in combination with temperature data, a long-term imbalance trend is extracted by using a moving average or median filtering algorithm, and real-time compensation is performed through a pre-calibrated temperature-drift function, so that the system maintenance period is remarkably prolonged.

The invention relates to the technical field of voltage acquisition, in particular to a battery string voltage acquisition system with a calibration system and a voltage acquisition method. Which comprises a multi-path voltage input end, a voltage signal adjusting end, a voltage follower, an analog-to-digital converter, a main control center and a communication circuit, and is characterized in that the voltage signal adjusting end comprises a dynamic voltage division network, consists of a digital potentiometer and a high-voltage operational amplifier, and dynamically adjusts the voltage division ratio to suppress common-mode voltage; the main control center is integrated with a multi-channel synchronous sampling calibration module and generates a global synchronous signal through the main MCU to control the ADC to perform synchronous acquisition; a temperature compensation module is arranged between the voltage follower and the ADC, and a digital temperature sensor is adopted to correct the gain drift of the operational amplifier in real time; the voltage division ratio of the dynamic voltage division network is dynamically adjusted according to the real-time common-mode voltage and a preset safety threshold value. According to the scheme, dynamic partial pressure adjustment, multi-channel self-calibration, nonlinear temperature compensation and a rapid protection mechanism can be integrated.

The invention discloses a high-current wide-capacitance-range LDO (Low Dropout Regulator) based on a frequency compensation circuit. The LDO comprises a first-stage operational amplifier, a second-stage operational amplifier and a third-stage operational amplifier The secondary operational amplifier is used for carrying out secondary amplification on the amplified error signal; the driving circuit is used for enhancing the driving capability of the error signal subjected to secondary amplification; the current output circuit is used for adjusting the output current of the output demand according to the secondary amplified error signal with the enhanced driving capability and the input voltage; the feedback circuit is used for generating new feedback voltage according to the output current; the first-stage operational amplifier is also used for amplifying a new error signal; and the frequency compensation circuit is used for adjusting the positions of a plurality of zero poles in the new error signal according to the output current by utilizing the multi-zero pole dynamic compensation branch and the current buffer compensation branch so as to offset a secondary pole and widen the whole unit gain bandwidth at the same time to obtain an adjusted error signal. According to the invention, a large bandwidth can still be obtained in a large current output range and a large load capacitance range.

The invention discloses a memristor-based signal detection circuit and method, a receiver and equipment, and relates to the field of wireless communication, a voltage source module of the circuit is connected with a voltage input end of a memristor array module, and a current source module is connected with a current input end of the memristor array module; the current output end of the memristor array module is connected with the reverse input end of the operational amplifier module and one end of the feedback resistor module, the other end of the feedback resistor module and the output end of the operational amplifier module are connected with the input end of the multiplier module, and the output end of the multiplier module is connected with one end of the resistor module. The voltage of the voltage source module is set according to the emission vector set; the current of the current source module is set according to the received radio frequency signal, and the conductance value of the memristor is set according to the channel matrix, so that a relatively low bit error rate of signal detection can be realized on the basis of greatly reducing calculation time and power consumption, and meanwhile, the requirement on programmable bit precision of the memristor is also reduced.

The invention relates to a high-precision temperature sensor based on complementary dynamic element matching and a zoom analog-to-digital converter and a working method, and belongs to the technical field of sensor improvement, and the sensor comprises an analog front end, an analog-to-digital converter, a digital rear end and a control logic. An improved chopping technology is adopted, and one clock signal is adopted to control two sub operational amplifiers, so that the output stability and precision of the analog front end are improved. A complementary dynamic element matching technology is utilized, errors caused by voltage drop at the two ends of a switch are reduced, the influence of channel charge injection is counteracted, a scaling type analog-to-digital converter design is provided for an analog-to-digital conversion part, and balance among power consumption, speed and precision is achieved. According to the method, a 10-bit successive approximation register analog-to-digital converter is used for measuring a numerical value and a change trend, and the numerical value and the change trend are analyzed, so that the expression effects of a current mirror structure, a transistor, a filter and the like are evaluated, the aging of the transistor is found in advance, and a clear direction is provided for future design improvement.

The invention provides a radio frequency front-end module. The radio frequency front-end module comprises a power amplifier, a single-pole double-throw radio frequency switch, a low-noise amplifier, a first single-pole single-throw radio frequency switch, a coupler, a double-pole double-throw radio frequency switch, a radio frequency amplifier, a second single-pole single-throw radio frequency switch, a detector and an operational amplifier. According to the radio frequency front-end module, when the processing capacity of the upper computer is weak or commands between the upper computer and the radio frequency front-end module are incompatible, the signal receiving capacity of the radio frequency front-end module can be improved, switching between a receiving bypass channel and a low-noise amplifier channel can be achieved in time, meanwhile, the complexity of transmitting power control is effectively reduced, radiation is reduced, and the reliability of transmitting power control is improved. The energy consumption is reduced, and the service life of the radio frequency front-end module is prolonged.

The embodiment of the invention provides a closed-loop control method for power driving and protection, and the method comprises the steps: constructing a voltage feedback type circuit through a high-speed operational amplifier, and forming a closed-loop gain structure through a feedback network of the voltage feedback type circuit; the load current of the output end of the voltage feedback type circuit is monitored in real time, and when the load current exceeds a first set threshold value, a protection mechanism is triggered to turn off the output stage; the power-on surge current is limited through the soft start control circuit; phase information of a load reflection coefficient is obtained, an inductance / capacitance combination of the variable dynamic impedance matching network is selected according to phase information table look-up, inductance / capacitance parameters are switched through a relay, and the transmission standing-wave ratio between the power amplifier and a load is optimized; monitoring the temperature of the radiating fin of the power tube, and dynamically adjusting the resistance value of the feedback network; and performing cooperative control of short-circuit protection, over-temperature protection and surge suppression according to the priority. According to the embodiment of the invention, the performance bottleneck in a load fluctuation scene is broken through.

The invention relates to the technical field of semiconductor laser power supplies, in particular to a semiconductor laser power supply control circuit based on linear constant current and a method thereof. According to the technical scheme, the circuit comprises a voltage follower module, a linear constant-current driving module, a power switch module, a pulse control module, a sampling feedback module and a follow current protection unit. The in-phase input end of an operational amplifier OPA320 of the voltage follower module is connected with external reference voltage # imgabs0 #, the inverted input end of the operational amplifier OPA320 is grounded through a first resistor R1 and connected with the output end through a second resistor R2, and a filter capacitor C1 is connected to the two ends of the second resistor R2 in parallel. Through a linear constant current control and pulse cooperation mechanism, the current stability and the dynamic response speed of the semiconductor laser under the wide-range and high-frequency working condition are remarkably improved, and it is guaranteed that the laser output power is accurate and reliable.

The present disclosure provides for transimpedance amplifiers for crossbar circuits. A crossbar circuit may include a plurality of bit lines intersecting with a plurality of word lines and a plurality of cross-point devices. Each of the plurality of the cross-point devices is connected to at least one of the word lines and at least one of the bit lines. The crossbar circuit may further include a transimpedance amplifier to generate an output voltage representative of a sum of currents flowing through a first bit line of the plurality of bit line. The transimpedance amplifier may include an operational amplifier, a current mirror circuit connected to an output of the operational amplifier, and one or more resistors connected to the current mirror circuit and a supply voltage.

The invention provides a current measuring circuit which comprises a micro-control unit and at least two measuring range circuits, and each measuring range circuit comprises a resistor, an MOS tube and an operational amplifier. The resistor of the previous measuring range circuit is connected in series with the resistor of the next measuring range circuit, the resistor of the first measuring range circuit is connected with power supply equipment, and the resistor of the last measuring range circuit is connected with a load to be measured; the micro-control unit is used for traversing the output voltage of the operational amplifier of each range circuit in sequence; if it is determined that target voltages on the two sides of a resistor of the measuring range circuit are smaller than a preset threshold value based on the output voltage, target current of a to-be-measured load is determined based on the output voltage and the resistance value of the resistor; and if the target voltage is not less than the preset threshold value, continuing to traverse the output voltage of the operational amplifier of the next range circuit. According to the technical scheme of the invention, the current measurement circuit meets the measurement requirements of a plurality of current ranges, the current ranges can be automatically switched, and the current output is not interrupted.

The present application discloses an anti-crosstalk sensing circuit of a capacitive pressure sensing array and a sensing method thereof, which relates to the field of capacitive pressure sensing technology. The circuit alternately inputs a positive excitation voltage and a negative excitation voltage at the driving end of each row of pressure sensing capacitors through a row selection state, and the detection end of each column of pressure sensing capacitors is respectively connected to the inverting input end and the reference voltage of the corresponding operational amplifier according to the column selection state, and obtains a first detection voltage and a second detection voltage corresponding to the positive excitation voltage and the negative excitation voltage output by the output end of the operational amplifier, respectively, and calculates the capacitance value of the pressure sensing capacitor of the target row based on the amplitude of the positive excitation voltage and the negative excitation voltage, the first detection voltage and the second detection voltage, and the capacitance value of the reference capacitor. The present application can prevent the crosstalk phenomenon between the same row or the same column of the capacitive pressure sensing array, and significantly improve the detection accuracy of the sensing circuit of the capacitive pressure sensor array for the sensing capacitor.

A driving method includes steps of: providing a source operational amplifier (SOP) to drive a display element; operating the SOP at a first bias current value when the display element is refreshed with a first refresh rate; and operating the SOP at a second bias current value different from the first bias current value when the display element is refreshed with a second refresh rate different from the first refresh rate.

The invention discloses a high-voltage power amplifier with an over-temperature and over-current protection circuit, and relates to the technical field of integrated circuits. The high-voltage operational amplifier comprises a high-voltage operational amplifier core unit and a self-adaptive protection circuit unit, the high-voltage operational amplifier core unit comprises a rail-to-rail input stage, a gain amplification stage and an AB type push-pull output stage which are sequentially cascaded, and the AB type push-pull output stage comprises a PMOS upper power tube and an NMOS lower power tube; the self-adaptive protection circuit unit comprises a PMOS (P-channel Metal Oxide Semiconductor) current-limiting protection circuit, an NMOS (N-channel Metal Oxide Semiconductor) current-limiting protection circuit and an over-temperature protection circuit; the PMOS current-limiting protection circuit is used for generating a high-voltage domain over-current control signal when the power tube on the PMOS is over-current; the NMOS current-limiting protection circuit is used for generating a low-voltage domain overcurrent control signal when the NMOS lower power tube is in overcurrent; the over-temperature protection circuit is used for generating high-voltage domain over-temperature turn-off signals and low-voltage domain over-temperature turn-off signals when the amplifier is over-temperature; and finally, carrying out logic synthesis on the corresponding over-current control signal and the over-temperature turn-off signal to generate a gate clamping signal.

The invention relates to the technical field of power supply control, and discloses a low power consumption circuit of a power supply management chip, which comprises a first operational amplifier, a third operational amplifier, a seventh trigger, a sixth resistor, a twelfth resistor, a fifteenth resistor, an eighteenth resistor, a first voltage stabilizing diode, a first switch, a first connector and a second connector, the in-phase end of the first operational amplifier is connected with one end of the first switch, the in-phase end of the third operational amplifier and one end of the fifteenth resistor, the other end of the first switch is connected with the end of the second connector, the anti-phase end of the first operational amplifier is connected with one end of the twelfth resistor, and the output end of the first operational amplifier is connected with the other end of the twelfth resistor. The inverting end of the third operational amplifier is connected with one end of a sixth resistor, the output end of the third operational amplifier is connected with the cathode of the first voltage stabilizing diode and the other end of the sixth resistor, a first pin and a fourth pin of a seventh trigger are connected with a power supply, and a third pin of the seventh trigger is connected with a first connector end.

The invention discloses a slew rate enhancement circuit of an operational amplifier, which comprises a comparison module used for comparing a positive input voltage and a negative input voltage of the operational amplifier and generating a first comparison signal and a second comparison signal according to a comparison result; the slew rate enhancing module is used for enhancing the slew rate of the falling edge of the output voltage of the operational amplifier according to the first comparison signal and enhancing the slew rate of the rising edge of the output voltage of the operational amplifier according to the second comparison signal; the common-mode feedback module is used for clamping the common-mode voltage of the first comparison signal and the common-mode voltage of the second comparison signal to a reference voltage when the operational amplifier is in a steady state, so that the slew rate enhancing module is in a closed state; therefore, the slew rate of the output voltage of the operational amplifier can be quickly enhanced when the operational amplifier has large step signal output, so that the output of the operational amplifier is quickly responded and established.

The invention discloses a high-voltage LDO turn-back type overcurrent protection feed-forward circuit and an overcurrent protection method based on the high-voltage LDO turn-back type overcurrent protection feed-forward circuit. The high-voltage LDO turn-back type overcurrent protection feed-forward circuit comprises an LDO loop and an overcurrent protection loop. The LDO loop is used for generating an output voltage according to an input reference voltage of the first operational amplifier and providing a detection current and a feedback voltage; the over-current protection loop is used for introducing detection current, so that the positive end voltage of the second operational amplifier is increased, when it is detected that the positive end voltage is higher than feedback voltage, over-current protection is triggered to open the switch current mirror, and the switch current mirror controls the output end voltage of the first operational amplifier; and the current of the output end of the first operational amplifier is accurately copied to the output end of the LDO loop.

Provided in the present application are a band-gap reference current source, a low dropout regulator and a power manager, which are applied to the technical field of power chips. The band-gap reference current source uses dual band-gap references to form a band-gap reference loop, and uses an operational amplifier clamping unit to implement clamping adjustment, so as to generate a reference current that is in direct proportion to the temperature, which is conducive to using the reference current to perform linear voltage stabilization subsequently, such that the regulator has a relatively high loading capacity, a very low quiescent current and a relatively high power noise suppression ratio, thereby improving the overall efficiency of a voltage-stabilizing circuit, and also greatly reducing the layout area.

The low-power fast wake-up band-gap reference voltage circuit operates in three phases: dormant, wake-up, and steady-state phases. The circuit enters wake-up subsequent to receipt of an enable signal which causes a one-shot timer to generate a slew enable signal pulse having a predetermined period. To a band-gap voltage reference circuitry comprising an operational amplifier, there is connected, at the wake-up phase, a boost circuitry, operative under the control of the slew enable signal that connects one or more of the one or more boost circuits to a band-gap voltage reference. Thereby, during the brief wake-up phase, more current is consumed to accelerate the response of the circuit. Upon completion of the wake-up phase the boost circuitry is disconnected under the control of the slew enable signal and for as long as the enable signal is active, the circuit is operative in a low-power mode.

The invention relates to the technical field of power supply circuits, in particular to a current sampling circuit, a chip and electronic equipment. The current sampling circuit comprises a first sampling branch, a second sampling branch and an operational amplifier, the sampling resistor is connected in series with a current branch to be measured; the output end of the first sampling branch is connected with the first input end of the operational amplifier; the first sampling branch is used for sampling first sampling voltage of the first end of the sampling resistor, and the second sampling branch is used for sampling second sampling voltage of the second end of the sampling resistor and outputting the second sampling voltage to the second input end of the operational amplifier; the operational amplifier is used for amplifying the difference value between the first sampling voltage and the second sampling voltage according to the amplification factor; the first sampling output end of the current sampling circuit outputs a first voltage value. When the current sampling circuit provided by the invention is used for high-side current sampling, errors caused by common-mode voltage are eliminated, so that the sampling precision is relatively high.

Systems and methods are provided for analog hardware realization of neural networks. The method includes obtaining a neural network topology and weights of a trained neural network. The method also includes transforming the neural network topology to an equivalent analog network of analog components including operational amplifiers and resistors. Each operational amplifier represents an analog neuron of the equivalent analog network, and each resistor represents a connection between two analog neurons. The method also includes computing a weight matrix based on the weights of the trained neural network. The method also includes generating a resistance matrix for the weight matrix. The method also includes pruning the equivalent analog network to reduce the number of operational amplifiers or the resistors, based on the resistance matrix, to obtain an optimized analog network of analog components.

The invention relates to the technical field of wireless communication networks, and provides a low-channel electroencephalogram amplification circuit and brain-computer interface equipment oriented to an after-ear electroencephalogram signal, and the low-channel electroencephalogram amplification circuit comprises a dry electrode sensing module which is used for collecting an electroencephalogram signal; the front active amplification module comprises an operational amplifier circuit with high input impedance; the anti-aliasing filtering module is formed by cascading a multi-order passive filtering network and an active filtering circuit, is connected with the output end of the front active amplification module and is used for filtering high-frequency interference signals; the right leg driving feedback module comprises a programmable impedance adjusting circuit and a current limiting protection circuit, the right leg driving feedback module and the front active amplification module form a closed-loop feedback loop, and the output end of the right leg driving feedback module and the human body form a current loop through a protection resistor; the analog-to-digital conversion module adopts an integrated low-power-consumption analog front-end chip; a wireless transmission module; and the power supply management module provides independent power supply for the analog front-end chip, the operational amplifier circuit and the wireless transmission module.

The invention belongs to the technical field of power electronics, and relates to a common-mode slip model active noise suppression circuit, which comprises a detection link, an amplification link, an injection link and a through-flow link, wherein the detection link detects the voltage of the ground, does not need a capacitor, and is directly connected to an inverted input end of an operational amplifier through a resistor for detection; an operational amplifier in the amplification link takes an N line as a reference, that is, an in-phase input end is connected with the N line, and the operational amplifier amplifies a voltage signal on the N line; in the injection link, an RC circuit composed of a resistor and a capacitor is mainly used for converting a voltage signal output by the operational amplifier into compensation current and injecting the compensation current back to the ground; a differential mode capacitor is used in the through-current link, a backflow path is provided for the compensation current, the compensation current of the two branches is balanced at the same time, and the differential mode noise of the system can be attenuated; according to the invention, common-mode noise can be converted into differential-mode noise, and the common-mode noise is reduced while the differential-mode noise is attenuated.

The invention belongs to the technical field of power electronics, and relates to a T-type active EMI filter which comprises a detection link, an amplification link, an injection link and a multiplexing link. The detection link is composed of a detection resistor and a detection capacitor and is used for providing an additional flow path for common-mode current; the amplification link consists of a resistor and an operational amplifier and is used for reversely amplifying voltage at two ends of the detection resistor; the injection link is composed of injection resistors and used for converting voltage signals output by the operational amplifier into compensation current and injecting the compensation current into the multiplexing link, the multiplexing link is composed of a first capacitor and a second capacitor, branches are provided for common-mode current and the compensation current, and meanwhile system differential-mode noise is attenuated; moreover, the T-type three-capacitor structure enables the active suppression circuit to be composed of an operational amplifier and a pure resistor. Therefore, the overall size of the active filter is reduced, design and use are simpler and more convenient, stability is better, and common-mode noise and differential-mode noise can be attenuated powerfully.

Disclosed in the present invention are a resistor-based voltage-withstanding on-state voltage drop measurement circuit for junction temperature monitoring, and a monitoring method. The measurement circuit comprises: a high-resistance series high-voltage resistor RL; switching diodes D1 and D2; a low-voltage MOSFET M1; a phase inverter U1; a three-state gate U2; an RC delay circuit consisting of a resistor R1 and a capacitor C1; current-limiting resistors R2 and R3; auxiliary voltage sources VDD and VCC; an operational amplifier U3; and an isolation operational amplifier U4. The monitoring method comprises: designing an on-state voltage drop sampling circuit based on a high-resistance resistor, and performing parameter selection on the basis of an actual application scenario; measuring a collector current and on-state voltage drop model at different junction temperatures under offline conditions, so as to provide a calculation model for online monitoring; and under online conditions, performing online monitoring of junction temperature on the basis of the model obtained by means of performing testing under the offline conditions. The present invention has the advantages of being low cost, having high reliability, and adaptability to on-state voltage drop measurement at a high voltage and within a wide ambient temperature range.

The invention provides a radio frequency front end module. The circuit comprises a first matching circuit, a first-stage power amplification circuit, a coupler, a first radio frequency switch, a radio frequency main path, an attenuation path, a second radio frequency switch, a second matching circuit, a second-stage power amplification circuit, a third matching circuit, a power detection circuit, a low-pass filter, a first operational amplifier and a hysteresis comparator. The hysteresis comparator is used for controlling the input end of the first radio frequency switch to be communicated with the first output end of the first radio frequency switch or the second output end of the first radio frequency switch; and meanwhile, the control circuit is used for controlling the first input end of the second radio frequency switch or the second input end of the second radio frequency switch to be communicated with the output end of the second radio frequency switch. According to the radio frequency front-end module, on the premise that the power amplification circuit is not damaged, normal output of the radio frequency signal can be ensured, and meanwhile the situation that a post-stage output signal is distorted due to reduction of the bias voltage is avoided.

A compensation circuit, including: a power management circuit and a switch circuit. The switch circuit is connected to a display panel and an operational amplifier circuit connected to the display panel. In case that a feedback voltage is greater than or equal to a target threshold, the switch circuit outputs a common voltage and an operating voltage to the operational amplifier circuit and stops outputting the common voltage to the display panel; and the operational amplifier circuit receives the common voltage and the operating voltage and outputs a compensation voltage to the display panel. In case that the feedback voltage is smaller than the target threshold, the switch circuit outputs the common voltage to the display panel and stops outputting the common voltage and the operating voltage to the operational amplifier circuit; and the operational amplifier circuit stops receiving the feedback voltage and stops outputting the compensation voltage.

The invention discloses a band-gap reference source high-order curvature compensation method based on an operational amplifier, and belongs to the technical field of high-precision analog integrated circuit design, and the method comprises the steps: generating an absolute temperature proportion PTAT current and an absolute temperature complementary CTAT current; generating a high-order curvature compensation voltage based on the PTAT current and the CTAT current; amplifying the generated high-order curvature compensation voltage through an operational amplifier, and superposing the amplified high-order curvature compensation voltage to a band-gap reference output stage to obtain compensated band-gap reference output voltage; and carrying out band-gap reference output calibration on the compensated band-gap reference output voltage so as to ensure that the temperature drift coefficient of the output band-gap reference voltage in the preset temperature range is smaller than a preset threshold value. According to the invention, high-order elimination of base-emitter voltage nonlinearity can be realized in a wide temperature range, and a relatively low temperature coefficient and low noise are achieved.

A regulator includes a voltage divider circuit that output, as a feedback voltage, a voltage generated by dividing an output voltage; an operational amplifier that compares the feedback voltage with a reference voltage; a drive transistor being disposed between a node at an input voltage and a node at the output voltage and that is controlled based on an output of the operational amplifier; a logic circuit that output an adjustment signal for the output voltage; and an output voltage adjustment circuit configured to adjust the output voltage based on the adjustment signal. The voltage divider circuit includes a plurality of resistors and a plurality of switches each of which is disposed in parallel with a corresponding one of the plurality of resistors. The output voltage adjustment circuit output, to the plurality of switches, a control signal in accordance with the adjustment signal, and the output voltage is supplied as a power supply voltage to the output voltage adjustment circuit.

The invention provides a current monitoring circuit, a chip and electronic equipment, and relates to the technical field of electronic circuits, and the circuit comprises a sampling circuit, an operational amplifier circuit and a signal processing circuit; the sampling circuit is connected with a sampling resistor of a monitoring target and outputs sampling voltage to the operational amplifier circuit; the operational amplification circuit outputs the sampling voltage difference after operational amplification to the signal processing circuit; the signal processing circuit comprises a multi-gear voltage generation module and a comparator, and the output end of the multi-gear voltage generation module is connected with the positive input end of the comparator so as to output target reference voltage to the comparator; the output end of the operational amplifier is connected with the negative input end of the comparator, the comparator outputs a feedback signal according to the target reference voltage and the sampling voltage difference, and the feedback signal is used for controlling the working state of a connecting chip; the multi-gear voltage generation module is used for generating reference voltages corresponding to different target currents. The method can adapt to multiple scenes with different current requirements.

The invention provides a signal acquisition system of a photoelectric detector. In the signal acquisition system, a transimpedance pre-amplification circuit is arranged at the output end of the photoelectric detector, and a passive high-pass filter circuit is connected between the transimpedance pre-amplification circuit and a post-voltage amplification circuit. And a feedback network is formed in the transimpedance pre-amplification circuit and is used for converting a current signal output by the photoelectric detector into a proportional first voltage signal and outputting the proportional first voltage signal. The filter circuit is a third-order LC high-pass filter circuit and is used for suppressing direct current, low frequency and self-beat frequency components and keeping a 10-90MHz pass band flat. The rear voltage amplification circuit adopts a voltage amplification structure of a voltage operational amplifier, the voltage gain Av is 6-10, and the super-band gain is limited through a shunt capacitor. According to the embodiment of the invention, through the structure and parameter setting, the noise gain peak value is suppressed, and the system stability is improved.