322 results about "Differential amplification" patented technology

The invention relates to the field of biomedical engineering, and discloses an embedded electroencephalogram signal collecting device and system.The device comprises a power management module, a plurality of electrode assemblies, a control module and a storage and communication module; through a control module designed by a system on chip SoC and a multi-electrode assembly in contact with intracranial nerves, the embedded electroencephalogram signal acquisition device which is in multi-level cooperation, supports user-defined sampling parameters and self-adaptive strategies and meets individual requirements of different focus monitoring scenes is constructed. High-precision distributed acquisition and self-adaptive processing of intracranial electroencephalogram signals are realized; a multi-electrode assembly is adopted, each assembly is provided with a plurality of contacts, the limitation of traditional single-point collection is broken through, different nerve areas are covered through the spatially distributed contact layout, and the focus positioning capacity is improved; the acquisition module effectively eliminates power supply ground wire interference and electromagnetic noise by using a differential amplification and common-mode rejection technology, and eliminates power frequency interference by combining band-pass and notch filtering to ensure the quality of an original signal.

The present application relates to the field of solution measurement, in particular to an electrode conductivity sensor conductivity measurement circuit and method, first, the AC excitation generation module generates an amplitude and frequency adjustable AC sine excitation signal under the control of the single-chip microcomputer; then the AC sine excitation signal passes through the precision resistor R0 and the conductivity cell of the electrode sensor to the system ground in turn; then the differential amplification circuit differentially amplifies the voltage between the precision resistor R0 and the electrode sheet of the conductivity cell; the amplified voltage signal is collected by the ADC, and then the voltage data is transmitted to the single-chip microcomputer; finally, the single-chip microcomputer can obtain the conductivity of the solution after the collected voltage data is operated. The present application directly collects the peak and valley voltage values of the AC signal, subtracts to obtain the amplitude of the AC signal, and does not need a rectification filter circuit to detect the amplitude of the AC signal, which can quickly respond to the change of the solution conductivity, eliminates the influence of common-mode interference factors, and simplifies the circuit design.

The invention discloses a gas concentration detection circuit and method based on differential measurement and reference compensation, and the circuit comprises at least one active gas sensitive element, the electrical parameters of which change along with the concentration of a target gas; the sensitivity of the reference gas sensitive element to the target gas is at least lower than that of the active gas sensitive element by a preset percentage threshold value; the active gas sensitive element and the reference gas sensitive element are connected in a differential pair form to form a differential signal generation unit; the differential amplification circuit is used for amplifying the differential signal output by the differential signal generation unit; the output signal of the differential amplification circuit is used for representing the concentration information of the target gas. According to the invention, environmental interference and baseline drift are directly and effectively suppressed from the hardware level, the stability and selectivity of gas concentration measurement are improved, and meanwhile, the holding circuit is simple in structure, low in cost and convenient for large-scale application.

The invention discloses an automatic temperature compensation circuit and method based on a thermal flowmeter, and relates to the technical field of temperature compensation, and the compensation circuit comprises a constant current source module used for driving the thermal flowmeter; the Wheatstone virtual bridge arm is used for acquiring a changed digital-to-analog converter output voltage value output by the controller, and performing voltage conversion on a first voltage and a second voltage which are output on the thermal flowmeter due to the change of the external temperature according to the output voltage value to obtain a third voltage; the digital-to-analog converter is used for performing correction compensation on the third voltage according to the correction compensation value calculated by the controller; and the differential amplification module adopts a differential amplifier to amplify the third voltage and the fourth voltage output by the thermal flowmeter, and outputs a compensated flow signal. The compensating circuit is simple in structure and higher in reliability and precision, and compared with a digital potentiometer, the output value of the Wheatstone virtual bridge arm is changed by using the output value of the digital-to-analog converter, so that the adjusting resolution is higher.

The invention discloses a seesaw type optical fiber end face weak force sensor which comprises a seven-core optical fiber, a seesaw type additive structure and an interference light beam. The seven-core optical fiber is composed of a central main fiber core and six symmetrically-distributed auxiliary fiber cores. The seesaw-type additive structure is composed of a short vertical beam, a vertical beam on a central main fiber core of the seven-core optical fiber and a cross beam connected to the vertical beam, and the whole structure is prepared through the two-photon polymerization technology of a femtosecond laser processing platform; the interference light beam is composed of two light beams in an interference cavity, wherein the lower surfaces of the left side and the right side of the seesaw-type additive structure are aligned with the end faces of two auxiliary fiber cores on the left side and the right side of the seven-core optical fiber. According to the invention, a two-photon polymerization technology is used to build an additive structure on the end face of the seven-core optical fiber, so that the sensing structure is small in overall size and is suitable for application in a limited space; the Fabry-Perot interferometers on the two sides of the sensing structure are connected in parallel to form an optical dynamic vernier structure, the sensitivity is improved through differential amplification of weak mechanical disturbance, and the anti-interference capability is enhanced through common-mode denoising.

A high-speed, low-noise laser signal detection apparatus, comprising a low-noise linear regulated power supply and a laser detection processing module. The low-noise linear regulated power supply (01-03) comprises an isolation unit (01), a voltage regulation and filtering unit (02), and a reference unit (03). The laser detection processing module (04-09) comprises a laser light signal detection input unit (05), a bias unit (04), a differential amplification unit (07), an active filtering unit (08), and an output interface unit (09). An output end of the voltage regulation and filtering unit (02) is connected to the reference unit (03) and the laser detection processing module (04-09). The reference unit (03) is connected to the bias unit (04) and is configured to provide a reference voltage to the bias unit (04). The bias unit (04) is configured to provide a bias voltage to the differential amplification unit (07). The differential amplification unit (07) comprises a multi-stage in-phase proportional differential amplification circuit, and the active filtering unit (08) comprises a multi-order active low-pass filter. According to the high-speed, low-noise laser signal detection apparatus, the detection bandwidth of a laser signal can be expanded, the signal-to-noise ratio of high-frequency pulse measurement can be reduced, and the anti-interference characteristics of a power supply can be improved.

The invention discloses a detection device and a detection system for harmonic oscillator capacitors of a hemispherical resonator gyroscope, and relates to the technical field of capacitor detection, the detection device comprises a signal detection circuit, a modulation compensation circuit, a differential amplification circuit and a control circuit, the signal detection circuit is connected with the output ends of the two harmonic oscillator capacitors; the modulation compensation circuit is correspondingly connected with two input ends of the signal detection circuit; the differential amplification circuit is correspondingly connected with two output ends of the signal detection circuit; the control circuit is configured to output modulation voltage to the two input ends of the modulation compensation circuit according to a voltage signal of the output end of the differential amplification circuit, and zero setting is carried out on voltage at the connecting positions of the two output ends of the modulation compensation circuit and the two input ends of the signal detection circuit. According to the invention, the modulation compensation circuit is adopted to enable the output ends of the two harmonic oscillator capacitors to work near zero voltage, the circuit has the characteristics of ultrahigh linearity, extremely low temperature drift, rapidness and stability, errors caused by power supply drift can be eliminated, and the detection precision is improved.

The invention discloses a silicon carbide MOSFET parallel current sharing system and method for a pulse power supply, and belongs to the technical field of SiC MOSFET parallel current sharing, the system comprises a main power circuit connected with a plurality of SiC MOSFETs in parallel and an active driving circuit, when the SiC MOSFETs are turned on, a source inductor generates an induced voltage in direct proportion to the current rising rate, and when the SiC MOSFETs are turned on, the active driving circuit drives the main power circuit to rotate; current sharing when a plurality of SiC MOSFETs are connected in parallel is realized through an in-phase amplification circuit used for detecting and amplifying an induced voltage, a differential amplification circuit used for detecting and comparing an induced voltage value, and a proportional current source circuit is controlled to extract a SiC MOSFET gate drive current. By adopting the method, the unbalanced current can be suppressed, the balance of the current flowing through each branch of the parallel SiC MOSFETs is ensured, the SiC MOSFET device in the high-voltage pulse power supply is effectively protected, and the working reliability of the circuit is improved.

The invention discloses an electric leakage detection method based on wavelet transform harmonic suppression, and the method comprises the steps: synchronously collecting a current signal through a dual-channel differential sampling circuit, and obtaining two paths of differential voltages; after common-mode interference is eliminated through differential amplification and impedance matching, low-pass filtering and digital conversion are carried out; extracting signal multi-scale energy characteristics by using wavelet decomposition, and setting a threshold value to separate leakage low-frequency components from high-frequency noise; a pure electric leakage signal is obtained through inverse wavelet reconstruction, and a high-speed switching circuit compares a preset threshold value to trigger a protection action. According to the scheme, differential sampling, impedance matching and wavelet analysis technologies are combined, the signal-to-noise ratio and the detection precision are effectively improved, the problems that in the prior art, electric leakage signals are prone to interference and slow in response speed are solved, and the reliability and the real-time performance of electric leakage protection are remarkably improved.

The invention provides an anti-interference pressure sensor signal conditioning circuit based on a differential amplification structure, and the circuit comprises a differential input module which is used for receiving a differential signal outputted by a pressure sensor, and carrying out the amplification and filtering of the outputted differential signal, and obtaining a first differential signal; the common-mode suppression module is electrically connected with the differential input module and is used for suppressing a common-mode signal in the first differential signal to obtain a second differential signal; the programmable gain amplification module is electrically connected with the common-mode suppression module and is used for performing programmable gain amplification on the second differential signal to obtain a third differential signal; the low-pass filtering module is electrically connected with the programmable gain amplification module and is used for filtering high-frequency noise in the third differential signal to obtain a fourth differential signal; and the output buffer module is electrically connected with the low-pass filtering module and is used for converting the fourth differential signal into a single-ended signal and outputting the single-ended signal. According to the invention, external electromagnetic interference and common-mode noise can be effectively suppressed, and the stability and accuracy of signal transmission are improved.

The invention provides a laboratory digital management method and system, electronic equipment and a storage medium, and relates to the technical field of laboratory automation and spectral analysis. The method comprises the following steps: acquiring a multi-wavelength spectral image sequence in an experimental reaction container in a non-contact manner, associating the multi-wavelength spectral image sequence with a final performance index, and performing differential enhancement to generate a spectral change feature map; performing differential amplification on the spectral electric signal to suppress noise and enhance an effective signal, dividing a region of interest according to a container structure, calculating average spectral intensity, and generating a spectral response curve; the method comprises the following steps: extracting first-order and second-order derivative curves, identifying an intensity change inflection point and a slope abrupt change interval, screening out a key optical change mode in combination with a final performance index, finally establishing a mapping relation between the key optical change mode and the performance index, and constructing a digital model for monitoring a reaction state and predicting final performance. The reaction process can be monitored and the experiment result can be predicted through the spectrum change characteristics, so that the intelligence and accuracy of laboratory management are improved.

The invention provides a temperature drift compensation method, device and equipment for a Hall current sensor, and relates to the technical field of Hall sensors. The method is applied to a temperature excursion compensation system, the temperature excursion compensation system comprises a temperature sensor, a microprocessor, a temperature excursion prediction model, a compensation signal generation module and a differential amplification circuit, and the temperature excursion compensation method comprises the following steps: acquiring environment temperature data of a Hall current sensor by using the temperature sensor; the microprocessor calculates a temperature drift error parameter corresponding to the current environment temperature data based on the environment temperature data and a temperature drift prediction model; the compensation signal generation module generates a corresponding compensation signal based on the temperature drift error parameter, and the compensation signal and the temperature drift error represented by the temperature drift error parameter are equal in size and opposite in direction; and superposing the compensation signal and an original sampling signal of the Hall current sensor through a differential amplification circuit to obtain a final current signal. The measurement accuracy of the Hall current sensor can be improved.

The invention discloses a single-power-supply ultra-wideband temperature compensation low-noise amplifier circuit, and belongs to the technical field of radio frequency microwaves. The circuit is mainly composed of a pre-stage low-noise amplifier module, an inter-stage temperature compensation equalization module and a post-stage driving amplifier module. The temperature compensation equalizer module generates differential voltage related to temperature through a three-stage gallium arsenide diode temperature sensing unit, outputs a control signal through an enhanced FET differential amplification circuit, drives a voltage-controlled attenuation equalizer to dynamically adjust the attenuation amount of a radio frequency signal, and achieves gain stability in a frequency band. Through the collaborative design of a blocking capacitor and a divider resistor, the grid bias of an FET switch is strictly limited in a transconductance linear adjustment interval, and the interval covers 80% of the effective range of the threshold voltage of a gallium arsenide FET tube. The circuit is powered by a single power supply + 5V, stable work of each module is ensured through active bias and a power supply filter network, and the circuit is suitable for extreme temperature environments such as high-frequency communication and radar.

The invention relates to the technical field of semiconductor lasers, in particular to an integrated double-closed-loop control surface emitting laser detection module and a control method.The detection module comprises an optical feedback unit which comprises photoelectric detectors integrated behind a gas chamber and beside a laser respectively and is used for detecting transmission light intensity and reflection light intensity; carrying out differential amplification according to the projection light intensity and the reflection light intensity so as to generate a wavelength locking feedback signal; the double temperature control unit comprises a temperature detection module and a heating module which are arranged at the air chamber and the laser, and is used for monitoring temperature signals at the air chamber and the laser and controlling the temperature of the laser and the air chamber through the heating module; and the cooperative control unit is connected with the optical feedback unit and the double temperature control unit and is used for adjusting the current and the temperature of the laser according to the wavelength locking feedback signal. According to the scheme of the invention, accurate wavelength-absorption peak matching is still maintained in a high-temperature environment, and the wavelength locking precision and the spectrum detection signal-to-noise ratio are effectively improved.

The invention relates to the technical field of photoelectric detection, and provides a single-photon counter circuit for weak light detection based on a photomultiplier, and the single-photon counter comprises a photoelectric conversion circuit, a differential amplification circuit, a threshold comparison circuit and a signal shaping circuit. The photoelectric conversion circuit is composed of a photomultiplier, a high-voltage power supply circuit and a voltage division circuit, detects weak light signals and outputs two paths of current signals through photoelectric conversion. The differential amplification circuit carries out differential amplification on the two current signals through a differential amplifier. The threshold comparison circuit compares two input signals, filters out signals with the amplitude lower than 1 / 2 of a set threshold, and outputs a single-path effective signal. And the signal shaping circuit shapes the effective signal and finally outputs the effective signal in a TTL pulse mode. According to the single photon counter circuit for weak light detection, the background dark counting rate is low, the sensitivity is high, and the counting unit module specially used for digital pulse statistics is connected behind the single photon counter circuit for counting single photons.

The embodiment of the invention discloses a non-blind area range resolution optimization laser wind measurement radar and a wind measurement method. The non-blind area range resolution optimization laser wind measurement radar comprises a seed laser; the beam splitter is used for splitting the single-frequency continuous light emitted by the seed laser into three paths: the short-distance detection emission unit is used for introducing a first path of laser and emitting the first path of laser to the atmosphere; the long-distance detection transmitting unit is used for introducing a second path of laser and transmitting the second path of laser to the main telescope; the main telescope is used for expanding the second path of laser and then emitting the second path of laser to the atmosphere, and is also used for receiving echo signals of the first path of laser and the second path of laser; the coherent beat frequency receiving light path processing unit is used for performing beat frequency amplification and differential amplification according to the received echo signals of the first path of laser and the second path of laser and the third path of laser and then converting the signals into electric signals; the processor is also used for carrying out range gate division and FFT processing on the electric signal according to a time sequence to obtain a frequency spectrum signal; and the inversion unit is used for inverting the wind speed data by using the frequency spectrum signal.

The invention provides a static frequency divider with adjustable self-resonant frequency and a clock circuit, and relates to the technical field of circuits, the frequency divider comprises a master latch and a slave latch; each of the master latch and the slave latch comprises a current source, an adjustable resistor unit, a differential amplification pair, a cross coupling pair and a load resistor pair; the current source is connected with the first current branch and the second current branch, the first current branch is connected with the load resistor pair through the differential amplification pair, the second current branch is connected with the load resistor pair through the cross coupling pair, the first current branch is provided with a first switching tube, and the second current branch is provided with a second switching tube and an adjustable resistor unit which are connected in series. Thus, the adjustable resistor unit is configured on the second current branch, association between the resistance value of the adjustable resistor unit and the frequency of the frequency divider is established, a hardware basis is provided for frequency adjustability, and frequency requirements of different scenes are met by adjusting the resistance value of the adjustable resistor unit and adjusting the self-resonant frequency of the frequency divider.

This invention provides a dual-end driven long shaft system multi-order torsional vibration test platform and a torsional vibration identification and suppression method, relating to the field of long shaft system variable frequency drive technology. The platform includes two dual-winding drive motors respectively located at both ends of the shaft system, a load motor located in the middle, and a switchable shaft system connection structure, along with a dual-master, dual-slave cooperative control system composed of four drive frequency converters. This method achieves controllable excitation of multi-order torsional vibration by superimposing the load torque step and the frequency excitation source. It utilizes differential amplification and dual-channel filtering in the signal processing module to extract speed fluctuation characteristics, accurately identifying the critical speeds of each order in the system. For the identified torsional vibration phenomenon, a speed differential negative feedback algorithm is used to correct the torque command of the frequency converter, and the torsional vibration energy of the elastic transmission chain is offset by actively enhancing the system's electrical damping. This invention solves the problem of reproducing complex torsional vibration under safe and controllable conditions and verifying suppression strategies in ultra-large generator units.

Bias circuits for CMOS power amplifiers are provided. The bias circuit includes a feedback module, a first bias module, and a second bias module. The feedback module has a first input connected to a output common mode voltage, a second input connected to a reference voltage, and an output connected to gates of main amplification transistors in a first differential amplification module; based on a difference between the output common mode voltage and the reference voltage, the feedback module adjusts gate voltages of main amplification transistors until the output common mode voltage is equal to the reference voltage; the first bias module provides bias voltages for the first differential amplification module; the second bias module provides bias voltages for a second differential amplification module. The present disclosure adopts direct negative feedback and cascoded current mirrors, which realize accurate DC gate bias and accurate control of the output common mode voltage.

The invention provides a bionic visual array system based on a two-dimensional negative capacitance phototransistor, and relates to the technical field of photoelectric detection, and the bionic visual array system comprises a MoS2 negative capacitance phototransistor, a voltage conversion circuit, a differential amplification circuit, a sampling hold circuit, a switching circuit and a voltage regulation circuit. The MoS2 negative capacitance photoelectric transistor is used for sensing a light signal to generate a light sensing current signal, the light sensing current signal is processed by the voltage conversion circuit, the differential amplification circuit and the sampling hold circuit and then a sampling hold signal is output, and the switching circuit controls the output of the sampling hold signal; the voltage adjusting circuit is used for adjusting the gate voltage of the gate of the MoS2 negative capacitance photoelectric transistor; the conduction threshold voltage of the MoS2 negative capacitance phototransistor is inversely correlated with the illumination intensity, and when the gate voltage is smaller than the dark state current turn-on voltage, the illumination sensitivity is positively correlated with the gate voltage; and the photosensitive modules sequentially output corresponding sampling holding signals according to a preset sequence. The system can realize data redundancy processing.

The utility model discloses a voltage and current rapid acquisition digital control circuit, which comprises a multi-channel digital-to-analog conversion circuit, and a voltage photoelectric isolation acquisition circuit and a current rapid acquisition circuit which are connected with the multi-channel digital-to-analog conversion circuit, and the multi-channel digital-to-analog conversion circuit comprises a multi-channel ADC chip. The output end of the multi-channel ADC chip is connected with an FPGA processor, and the multi-channel ADC chip is used for converting the analog quantity of accessed voltage and current signals into digital quantity data and transmitting the digital quantity data to the FPGA processor in a bus mode. According to the utility model, the photoelectric isolator whose maximum delay time from input to output does not exceed 3.3 [mu] s can be used to realize signal photoelectric isolation amplification, the differential amplification filter circuit is connected in parallel with a 1nF capacitor to give consideration to both signal filtering stability and capacitor charging rapidity, and the ADC conversion chip whose resolution is 16bit and capable of parallel acquisition is selected. And multi-channel high-precision and rapid parallel analog-to-digital conversion is realized.

The invention discloses a printer motor control method and system based on a current detection front-end conditioning circuit, and relates to the technical field of current detection, and the current detection front-end conditioning circuit comprises a precise sampling resistor and a multi-stage RC filter network; the method comprises the following steps: collecting a motor phase current signal through a current detection front-end conditioning circuit, and converting the motor phase current signal into a digital current signal after differential amplification and filtering; obtaining a direct-axis current component and a quadrature-axis current component through coordinate transformation; setting a reference quadrature-axis current, and setting a direct-axis current reference value as 0; calculating a direct-axis voltage and a quadrature-axis voltage, and generating a switching signal for driving an inverter; in each control period, performing median filtering on the current sampling signal to adjust the integral gain of the PI controller; and identifying the abnormal state of the motor based on the time domain characteristics of the digital current signal so as to adjust the operation strategy of the 3D printer. High-precision current sensing and abnormal state recognition are both considered, and the printing quality of the 3D printer is improved.

The application discloses to the technical field of differential amplifier, specifically a differential amplifier circuit with high common-mode input voltage, comprising: an internal differential amplification circuit for processing input signals; a power supply voltage detection module for detecting an external power supply voltage for powering the circuit and outputting a detection signal; a charge pump module for boosting the external power supply voltage to generate a boosted power supply; a control module coupled with the power supply voltage detection module and the charge pump module respectively for receiving the detection signal and controlling the working state of the charge pump module based on the detection signal; based on this, the application has the effect of enabling the chip to maintain high common-mode input voltage processing capability and high common-mode rejection ratio within the full power supply voltage range, and can stably process high common-mode signals without relying on a specific numerical high-voltage power supply, solving the problem of sharp performance decay under low power supply voltage in the prior art.

The invention discloses a tumor detection device and method based on a diamond quantum sensor, and belongs to the technical field of biomedical detection. The device comprises an optical fiber laser, an optical fiber beam splitter, an optical fiber attenuator, an optical fiber circulator, an optical filter, two photoelectric detectors, a differential amplifier, an electronic filter, a computer, a signal generator, two microwave antennas and an optical fiber probe. The optical fiber probe comprises an optical fiber packaged in a plastic shell, a diamond quantum sensor which is fixed at the tail end of the optical fiber and comprises an NV color center, and a first microwave antenna integrated beside the optical fiber. The laser excites the diamond to generate fluorescence, meanwhile, the signal generator drives the two microwave antennas to apply a microwave field, and the dielectric property of the sample to be detected modulates the fluorescence intensity of the diamond by influencing the microwave field. Laser noise is eliminated through a differential amplification and filtering technology, and fluorescence signal change is analyzed by a computer, so that dielectric constant distribution of a sample is reconstructed, and non-invasive and high-sensitivity detection of tumors is realized.

The application belongs to the technical field of polarization loss compensation, and particularly relates to a polarization loss compensation device and method in high-speed electro-optical response measurement. The device adopts PBS light splitting, one way of which is input to a broadband photodetector, and the other way is input to a photodetector and subjected to I / V conversion. By monitoring the ratio of the current value of the broadband photodetector to the I / V conversion value, the effect of differential amplification maximization can be achieved, and the method has higher detection sensitivity. The application monitors the input light, can overcome the polarization misjudgment caused by the power fluctuation of the input light signal, combines the power value fluctuation for compensation, and can ensure more accurate electro-optical signal polarization state adjustment and improve tracking accuracy.

The invention discloses a high-temperature dynamic strain test system and method, and relates to the technical field of high-temperature vibration test and strain measurement, and the system comprises a high-temperature loading measurement unit, a signal extension shielding line and a signal conditioning unit. The high-temperature loading measurement unit comprises a high-temperature strain measurement sheet and a compensation sheet which are respectively adhered to the tested piece and the accompanying test piece, and the high-temperature strain measurement sheet and the compensation sheet are in common-ground connection through a shielding layer by adopting a five-wire wiring method; the signal conditioning unit adopts a symmetrically-arranged double constant current source power supply and differential amplification structure, so that sensitivity deviation and common-mode noise interference caused by lead resistance change are effectively inhibited; according to the method, the maximum strain point is accurately positioned through the combination of finite element simulation and test, a dynamic resistance signal is directly converted by adopting constant-current excitation, and accurate acquisition of a strain signal in a high-temperature vibration environment is realized. According to the invention, the problems of obvious lead resistance influence and insufficient noise suppression capability in traditional measurement are solved, and high-precision and high-reliability measurement of dynamic strain of high-temperature parts such as aero-engine blades is realized.

The utility model relates to a battery-powered intelligent differential pressure flowmeter, which comprises a microcontroller M261, and a power supply module, an LCD (liquid crystal display) display module, a key input module, a communication module and a sensor module which are respectively connected with the microcontroller M261, the power supply module comprises two switchable power supply modes, namely an external photovoltaic voltage input mode and a built-in lithium battery mode, and a power supply stably outputs voltage for the microcontroller M261 to use through a low dropout regulator LDO; the sensor module comprises a differential pressure sensor, a compensation pressure sensor, a flow medium compensation temperature sensor and an NTC sensor. The differential pressure sensor, the compensation pressure sensor and the flow medium compensation temperature sensor are connected with differential amplification circuits respectively, the three differential amplification circuits are connected with the microcontroller M261 through the analog-to-digital converter, and the NTC sensor is connected with the microcontroller M261 through the analog-to-digital converter. Two power supply modes are supported, flexible use is facilitated, the power consumption of the whole machine is effectively reduced due to the circuit design, and the working time of the battery is prolonged.

The invention discloses a circuit for simplifying electroencephalogram signal detection, amplification and transmission, and relates to the technical field of electroencephalogram signal acquisition. Comprising a distributed JFET signal amplification module, a differential amplification and common-mode recovery module and a differential-to-single-ended module. The distributed JFET signal amplification module directly amplifies weak electroencephalogram signals at an electroencephalogram signal acquisition point, and noise is reduced and measurement errors caused by Vos are eliminated through cooperation of a JFET tube and an operational amplifier in combination with a reference current source and a zero setting circuit; the differential amplification and common-mode recovery module further amplifies the amplified differential signal and recovers a common-mode signal, so that the influence of the input current on a pre-stage circuit is reduced; the differential-to-single-ended module converts the differential signal into a single-ended signal and couples the single-ended signal to a specified common-mode voltage, so that ADC acquisition is facilitated. Interference in the electroencephalogram signal transmission process is effectively reduced, the authenticity and accuracy of signal collection are improved, complex digital bus control is not needed, the number of connecting lines is reduced, and connection between point locations is simplified.

The application provides a metal film thickness measurement method and device for tungsten gate chemical mechanical polishing, comprising a sensor probe, a power module, a signal excitation module, a differential amplification module, a synchronous demodulation module, a data acquisition and processing module; the sensor probe comprises coaxially arranged excitation coils, detection coils and balance coils; the signal excitation module drives the three-coil resonance module to induce eddy current effect at the metal film to be measured; the differential amplification module converts the equivalent impedance change caused by the eddy current effect in the coils into a differential signal, and simultaneously improves the dynamic range through low-noise amplification; subsequently, the synchronous demodulation module multiplies the differential signal with a reference signal, and extracts a direct current component proportional to the signal amplitude through a low-pass filter; the obtained voltage amplitude signal is input into the data acquisition and processing module; the application can significantly amplify the weak signal related to the film thickness, effectively suppress common-mode noise, obtain nanometer-level thickness resolution, and has a high signal-to-noise ratio.

This application relates to the field of microphone technology, and discloses a differential amplifier circuit and a desktop microphone. The circuit is used to amplify and process the differential audio signal of the desktop microphone. Its features include an input signal receiving and DC bias module, a differential transistor amplifier module, a fully differential operational amplifier module, a cross-feedback network module, a power supply and reference voltage module, and an output signal processing module connected in sequence. A common-mode negative feedback network for suppressing common-mode signals is provided between the emitters of the two corresponding symmetrical amplification paths of the differential transistor amplifier module. A cross-feedback network module is provided between the differential output terminal and the differential input terminal of the fully differential operational amplifier module to form an AC differential negative feedback loop. The power supply and reference voltage module includes at least two reference voltage units, which respectively provide DC bias for the differential transistor amplifier module and set the output common-mode level for the fully differential operational amplifier module.