224 results about "Instrumentation amplifier" patented technology

The invention discloses an output voltage detection method and system based on an aviation power supply, and relates to the technical field of aviation power supply voltage detection. A differential voltage sensor is connected to the output end of an aviation power supply, a high-frequency suppression capacitor is connected in parallel, the sampling rate of 20-50 times of the working frequency is set according to the type of the power supply, and the signals are collected and converted into analog voltage signals; the analog signal is subjected to two-stage filtering, is amplified to 0-5V through an instrument amplifier, and is converted into a digital voltage sequence through a 16-bit ADC (Analog to Digital Converter); calculating AC power supply effective value, peak value and other parameters, DC power supply average value, ripple coefficient and other parameters; comparing the characteristic parameters with a preset threshold value, determining that the characteristic parameters exceed the threshold value and recording related information; and a detection result is transmitted to a monitoring terminal through an RS485, data is locally stored, and a switching value is output to an alarm device when the data is abnormal. The method adapts to aviation power supply load fluctuation and environment temperature change, detection precision is high, data transmission and storage are safe, abnormity is accurately identified and early warning is carried out in advance, and aviation power supply operation and maintenance reliability and efficiency are improved.

The various implementations described herein include techniques and apparatuses for multi-channel biopotential signal acquisition, biopotential signal pre-processing, and adaptive signal conditioning. In one aspect, an analog frontend circuit includes an instrumentation amplifier (INA) and an analog-to-digital circuit (ADC) in a forward signal path. A digital circuit receives input from the ADC. An adaptive baseline tracking and compensation circuit tracks and compensates moving motion artifact driven changes. A power line interference (PLI) detection and compensation circuit tracks a desired number of PLI harmonics, and magnitude, phase and frequency for the PLI harmonics in real time. A digital-to-analog converter (DAC) circuit combines output of the adaptive baseline tracking and compensation circuit and the PLI detection and compensation circuit to output an analog output. A passive filter receives the analog output and drives an analog compensation signal at an input of the INA.

The invention discloses an amplifying circuit for improving a common-mode rejection ratio, relates to the field of sensor analog front-end circuits, and aims to improve the common-mode rejection ratio of a circuit system by suppressing common-mode signal change and differential-mode signals caused by the common-mode signal change. A capacitive coupling structure and a chopping stabilizing circuit are combined, so that the problems of an instrument amplifier with a three-operational-amplifier structure are solved, firstly, the amplifier drives a passive network, and the power consumption is reduced; secondly, the AC capacitor is connected in series to isolate a common-mode signal, so that the CMRR of the circuit is improved; thirdly, the chopping stabilizing circuit modulates the offset voltage and the common-mode signal change voltage to high frequency, the offset voltage and the common-mode signal change voltage are filtered by a filter, the circuit gain is improved, and meanwhile, the CMRR is also improved; and fourthly, the problems of residual offset and output ripple caused by the chopper circuit are reduced through the DSL and the RRL, so that saturation of a post-stage circuit is avoided.

The invention relates to the technical field of power grid measurement, in particular to a miniaturized wireless self-powered alternating current electric field measurement method and system. Comprising the following steps: acquiring radio frequency energy in an electric field environment, and converting the radio frequency energy into direct current electric energy through a radio frequency energy acquisition system consisting of a microstrip antenna, a voltage doubling rectifying circuit and an energy management circuit; an alternating current electric field signal is collected through a differential dual-electrode sensor structure, and an electric field voltage signal is generated; amplifying the voltage signal through an instrument amplifier, and obtaining a digital signal of the electric field signal through an analog-to-digital conversion circuit; and processing and analyzing the alternating current electric field information according to the digital signal. By combining a radio frequency energy acquisition technology with a differential dual-electrode sensing structure, the electric field sensor has the performance characteristics of self energy supply, miniaturization, high precision, wide frequency response and low power consumption. The system can measure various types of electric field signals, including sine wave, triangular wave and square wave electric field signals, has a wide frequency range and a wide measuring range, and is excellent in linearity.

The invention discloses a low-noise and high-precision analog front-end circuit for biological signal acquisition. The low-noise and high-precision analog front-end circuit comprises a chopping capacitance coupling type instrument amplifier circuit, a switched capacitor type programmable gain amplifier circuit and a Sigma-Delta analog-to-digital converter modulator circuit. T-type capacitance feedback, chopping modulation and programmable technologies are introduced on the basis of an existing amplifier, and the low-noise and programmable gain functions of the pre-amplifier are achieved. Through the three-order one-bit quantized feed-forward chopping type Sigma-Delta modulator, the signal to noise ratio and the effective bit number of the signal are improved. Compared with the prior art, the analog front-end circuit not only has the capability of changing the gain multiple according to the bio-electricity signal, but also has the low-noise and high-precision signal processing effect, and the problems that a traditional analog front-end circuit is large in noise and low in signal processing precision are solved. In addition, the biological signal acquisition-oriented circuit provided by the invention can also be used in other analog front ends, such as an audio processor and the like, and is wide in application range.

The invention provides a temperature sensor for rapid calibration and a calibration method of the temperature sensor, and the temperature sensor comprises a bias module which is used for providing a bias current for a temperature sensing module; the temperature sensing module is used for determining a first VBE voltage and a second VBE voltage according to the bias current, generating a voltage signal in positive correlation with the temperature through a VBE voltage difference between the first VBE voltage and the second VBE voltage, and transmitting the voltage signal to the analog-to-digital conversion module and the instrument amplifier respectively; the analog-to-digital conversion module is used for determining a first temperature value through the voltage signal and the original reference voltage of the temperature sensor; the instrument amplifier is used for determining a second temperature value through the voltage signal; wherein the temperature difference value between the first temperature value and the second temperature value is used for calibrating the original reference voltage to obtain the target reference voltage. According to the embodiment of the invention, the environment requirement for temperature sensor chip calibration can be greatly reduced, the calibration time of the chip is shortened, and the production efficiency of the chip is improved.

The utility model aims to provide the testing device based on the arm model heat flow, which is low in cost, can meet uv-level voltage testing requirements, can realize voltage testing of a plurality of channels, and can improve the testing efficiency. The device comprises an arm model, a heat flux sensor, a temperature sensor, an operational amplifier, an instrumentation amplifier, an analog-to-digital converter and a main control board, the heat flux sensor and the temperature sensor are both mounted on the surface of the arm model, the temperature sensor is mounted on the surface of a product, the temperature sensor is connected with the main control board, and the operational amplifier is connected with the main control board. The heat flux sensor is connected with the input end of the operational amplifier, the operational amplifier increases input impedance, the output end of the operational amplifier is connected with the input end of the instrument amplifier and amplifies and converts signals into differential analog signals, the output end of the instrument amplifier is connected with the 24-bit analog-to-digital converter, and the analog-to-digital converter is connected into an external upper computer through the main control board. The device is applied to the technical field of heat flux testing.

The invention relates to the technical field of amplifiers, and discloses an analog-to-digital converter combination instrument amplifier which comprises a first-stage amplifier, the first-stage amplifier is in signal connection with a second-stage amplifier, the second-stage amplifier is in signal connection with a front-end low-pass filter (LPF), the front-end low-pass filter (LPF) is in signal connection with an analog-to-digital converter (ADC), and the analog-to-digital converter (ADC) is in signal connection with the analog-to-digital converter. And an unbalanced input-to-balanced differential circuit output module is arranged between the second-stage amplifier signal and a front-end low-pass filter (LPF). From the perspective of signal processing and conversion, a precise signal transition bridge is constructed by adding an unbalanced input-to-balanced differential circuit output module, unbalanced signals output by a second-stage amplifier are converted into double-end balanced differential signals, common-mode noise interference is effectively resisted through a differential transmission mode, the signal purity is guaranteed, and the signal quality is improved. The front-end low-pass filter and the analog-to-digital converter are adaptive to differential signals, so that the signal transmission is stable and anti-interference, and the analog-to-digital conversion is more accurate.

The invention provides a frequency converter embedded current waveform analysis method and system and a medium, and relates to the technical field of current waveform analysis, and the method comprises the steps: obtaining a sampling circuit configured in a current path of a frequency converter; calculating the required total gain based on the original output voltage signal of the sampling resistor and the required input voltage of the analog-to-digital converter; the signal quality of the original output voltage signal is evaluated, the required total gain is dynamically distributed to an instrument amplifier and a programmable gain amplifier, the original output voltage signal is amplified and then passes through an analog-to-digital converter, and current waveform data is obtained for current anomaly analysis; when the signal quality is lower than a first threshold value, the gain share of the instrument amplifier is increased preferentially; when the signal quality is higher than a second threshold, the gain share of the programmable gain amplifier is increased preferentially. According to the invention, the technical problem of low accuracy of current waveform analysis in the prior art can be solved, and the technical effect of improving the accuracy of waveform analysis is achieved.

The various implementations described herein include techniques and apparatuses for multi-channel biopotential signal acquisition, biopotential signal pre-processing, and adaptive signal conditioning. In one aspect, an analog frontend circuit includes an instrumentation amplifier (INA) and an analog-to-digital circuit (ADC) in a forward signal path. A digital circuit receives input from the ADC. An adaptive baseline tracking and compensation circuit tracks and compensates moving motion artifact driven changes. A power line interference (PLI) detection and compensation circuit tracks a desired number of PLI harmonics, and magnitude, phase and frequency for the PLI harmonics in real time. A digital-to-analog converter (DAC) circuit combines output of the adaptive baseline tracking and compensation circuit and the PLI detection and compensation circuit to output an analog output. A passive filter receives the analog output and drives an analog compensation signal at an input of the INA.

The invention discloses an analog quantity detection system with a protection circuit, and relates to the analog quantity detection system with the protection circuit, which comprises a detection circuit connected with an analog signal through a wiring terminal, the protection circuit and an MCU (Microprogrammed Control Unit), compared with a detection system of a traditional operational amplifier, the instrument amplifier is adopted for detection, and the detection system has the advantages of being ultrahigh in input impedance, extremely good in CMRR, low in input offset, low in output impedance and capable of amplifying signals under common-mode voltage. The circuit also has the functions of high common-mode rejection ratio, low noise, low linear error, low offset voltage and offset voltage drift, and low input bias current and offset current error, and by arranging an AD input clamping protection circuit, when the system has a fault and the voltage suddenly rises, the clamping function is realized by using the unilateral conductivity of a diode, and the phenomenon that the voltage of a sampling port is larger than 5V is prevented. And the ADC port of the MCU is damaged.

The high-precision NDIR gas sensor comprises a gas detector, a signal processing circuit, a microprocessor with an analog-to-digital converter (ADC), a light source driving circuit, a power conversion circuit, a communication module and circuit, a screen driving circuit and a display. The signal processing circuit carries out preliminary amplification and analog filtering on output signals of the detector through an instrument amplifier, a band-pass filter and isolation, noise can be effectively removed, and the characteristics of target signals can be enhanced. A microprocessor with an analog-to-digital converter (ADC) collects signals and achieves digital filtering through FFT conversion, the signal quality is further optimized, and finally the detected gas concentration value is displayed on a display screen in real time. The system can realize high-efficiency signal processing on the premise of ensuring real-time performance, has the advantages of simple structure, easy realization, low cost and the like, and is suitable for various signal processing scenes including but not limited to the fields of industrial automation, sensor data processing, medical signal analysis and the like.

The invention relates to the technical field of integrated circuits, and discloses a high-pass filter circuit and a low-noise and high-common-mode-rejection-ratio high-speed instrument amplifier, and the low-noise and high-common-mode-rejection-ratio high-speed instrument amplifier comprises a high-pass filter circuit which is used for providing a high-pass filtering function; the input end of the current feedback instrument amplifier circuit is connected with the high-pass filter circuit and used for providing high input impedance and a high common-mode rejection ratio, and the input end of the transconductance amplifier circuit is connected with the output end of the current feedback instrument amplifier circuit and used for improving the load driving capacity; wherein the high-pass filtering circuit adopts a connection mode of a small-capacitance capacitor and an adjustable pseudo resistor to realize high-pass filtering, and the small-capacitance capacitor refers to an on-chip capacitor of which the capacitance value is less than 100pF so as to realize complete integration. The instrument amplifier effectively solves the problem that a traditional instrument amplifier cannot have high speed, low noise, high common-mode rejection ratio and direct-current voltage offset suppression at the same time.

The invention aims to provide a measuring device and a testing method for an audio amplifier module. The system comprises a main control board, a DMM test board, a frequency processing board, a test signal adapter board and a to-be-tested audio module, the to-be-tested audio module is connected to the frequency processing board through the test signal adapter board, the frequency processing board is connected to the main control board through the DMM test board, the frequency processing board is connected with the main control board, and the to-be-tested audio module is connected with the main control board through the DMM test board. The frequency processing board comprises a converter, a comparator, an instrumentation amplifier and an operational amplifier, the input end of the instrumentation amplifier is connected with an audio module to be tested, the IN1 end of the converter is connected with the output end of the instrumentation amplifier and the reverse input end of the comparator, the VOUT end of the converter is connected with the DMM test board, and the operational amplifier is connected with the DMM test board. And the non-inverting input end of the comparator is connected with the operational amplifier. The method is applied to the technical field of alternating signal measurement.

The invention discloses a signal acquisition circuit for a brain-computer interface, and relates to the technical field of integrated circuits. The acquisition circuit comprises a sensing amplifier, wherein the sensing amplifier comprises a chopping modulation capacitance coupling instrument amplifier and a band-pass filter which are connected in series; the chopping modulation capacitance coupling instrument amplifier comprises an input main chopping modulator, an input capacitor, a negative feedback circuit, a first amplification circuit and a second amplification circuit which are sequentially connected in series; a pre-charging circuit, an input capacitor and a first amplifying circuit are connected to the input main chopping modulator in parallel, a positive feedback enhancing loop is connected to a second amplifying circuit in parallel, the first amplifying circuit and the second amplifying circuit are connected with a first direct-current servo loop and a negative feedback circuit in parallel, and a ripple suppression loop is connected to the second amplifying circuit in parallel. And the second amplification circuit is connected with the signal output end through the band-pass filter. The sensing amplifier in the acquisition circuit can output the electroencephalogram signals with higher quality, so that the quality of the acquired brain-computer interface signals is higher.

The invention belongs to the related technical field of industrial displacement measurement, and discloses a half-bridge strain gauge displacement sensor signal conditioning circuit which comprises a half-bridge Wheatstone circuit module with manual zero setting, an RFI filtering module, a primary instrument operational amplifier module, a secondary precision amplifier module, an RC filtering module and a reverse following module which are sequentially connected in series. The half-bridge Wheatstone circuit module comprises a manual zero setting half-bridge Wheatstone circuit module and is used for dynamically compensating millivolt-level offset voltage caused by tolerance of a strain gauge and a fixed-value resistor; the RFI filtering module is used for suppressing rectification errors caused by radio frequency interference; the RC filtering module is used for suppressing high-frequency noise and smoothing a signal waveform; the reverse following module is used for realizing impedance isolation; two resistors are connected into a half-bridge Wheatstone circuit to form a manual zero setting module, millivolt-level offset voltage caused by tolerance of a strain gauge and a fixed-value resistor is dynamically compensated, and the problem that a traditional bridge sensor is insufficient in offset voltage and signal-to-noise ratio is solved.

The invention relates to the technical field of measurement of long-distance and high-accuracy temperature measurement resistors, and particularly discloses a resistor temperature measurement method, which comprises a constant current source I, temperature measurement resistors RX and RY, a reference resistor RR, an analog switch, an instrument amplifier, an analog-to-digital converter and a microcontroller, the method comprises the following specific steps that S1, an analog switch controls a constant current source I to sequentially flow through temperature measurement resistors RX and RY and a reference resistor RR, and current generates a voltage on each resistor and is in direct proportion to the resistance value of the voltage; and S2, measuring the voltages of the temperature measuring resistors RX and RY and the reference resistor RR through an instrument amplifier and an analog-to-digital converter to obtain VX1, the voltage of the temperature measuring resistor RX under the forward current condition, VY1, the voltage of the temperature measuring resistor RY under the forward current condition, and VR1, the voltage of the temperature measuring resistor RR under the forward current condition. According to the resistance temperature measurement method, 0.00025 DEG C or better uncertainty can be obtained, and observable errors caused by thermoelectromotive force can be effectively eliminated.

The application discloses a kind of multi-modal flexible sensor adaptive signal conditioning system design method, belong to flexible sensor signal conditioning technical field.The present application overcomes the defects of poor universality, performance compromise, high cost of mass production of existing conditioning circuit, adopts layered decoupling and dynamic reconstruction system-level architecture: through multi-modal feature analysis and demand mapping modeling, the feature vector composition of scene recognition is determined;Design configurable analog front end, integrate instrument amplifier, transimpedance amplifier, charge amplifier, bridge amplifier four parallel processing sub-modules, wherein charge and bridge amplifier adopt self-designed architecture with dynamic adaptive gain adjustment capability;Build heterogeneous digital processing platform with NPU, CPU, DSP as core, through cross-modal data fusion, scene recognition engine, dynamic hardware configuration combined with feedforward and feedback, loadable algorithm library and closed-loop optimization control law, realize the real-time scene reconstruction of hardware parameters and digital algorithm;Combined with domestic single-chip selection, rigid-flex PCB and automatic calibration, meet the demand of low-cost mass production.The present application realizes the native adaptation and performance optimization of single hardware platform to voltage, current, charge, impedance and other types of sensor signals, and can be widely applied in robot dexterous hand, medical monitoring, intelligent bandage, consumer motion monitoring and industrial monitoring fields.

The present invention herein is a method and apparatus that significantly limits the effect of high frequency (“HF”) interferences on acquired electro-physiological signals, such as the EEG and EMG. Preferably, this method comprises of two separate electronic circuitries and steps or electronics for processing the signals. One circuit is used to block the transmission of HF interferences to the instrumentation amplifiers. It is comprised of a front-end active filter, a low frequency electromagnetic interference (“EMI”) shield, and an isolation barrier interface which isolates the patient from earth ground. The second circuit is used to measure the difference in potential between the two isolated sides of the isolation barrier. This so-called “cross-barrier” voltage is directly representative of the interference level that the instrumentation amplifier is subjected to. This circuit is used to confirm that the acquired signals are not corrupted by the interference.

There is provided a circuit comprising a mirrored enhanced Howland current source, the mirrored enhanced Howland current source comprising an input and an output; and a feedback loop, the feedback loop comprising: an instrumentation amplifier arranged to measure a current at the output of the mirrored enhanced Howland current source; a comparator arranged to compare an output of the instrumentation amplifier to a reference voltage source; an integrator electrically coupled to the output of the comparator; a multiplier arranged to multiply the output of the integrator with the reference voltage, wherein the output of the multiplier is electrically coupled to the input of the mirrored enhanced Howland current source.

A sensor amplifier circuit includes a differential amplifier circuit and a compensation circuit. The differential amplifier circuit is configured to amplify a difference voltage between a pair of output signals from a sensor circuit and generate an output voltage. The compensation circuit is configured to generate a compensation signal based on the output voltage to compensate for a non-linear distortion of the output voltage. The differential amplifier circuit includes a current feedback instrumentation amplifier (CFIA). The compensation circuit includes one or more operational transconductance amplifiers (OTAs) configured to output one or more electric currents based on the output voltage and outputs a sum of the one or more electric currents from the one or more operational transconductance amplifiers as the compensation signal. The compensation signal from the compensation circuit is input to a current feedback loop in the current feedback instrumentation amplifier.

The invention discloses a constant transconductance circuit of a DDA instrument amplifier and the DDA instrument amplifier. The constant transconductance circuit comprises BJT input pair transistors and is used for converting a pair of differential input voltages into a pair of differential output currents and generating a pair of emitter voltages and a pair of collector voltages. When the pair of differential input voltages changes, the transconductance replica circuit generates transconductance replica current according to the pair of collector voltages so as to introduce the current change generated by the BJT input pair transistors along with the change of the pair of differential input voltages into the source degeneration circuit. Furthermore, a constant ratio between the pair of differential output currents and the pair of differential input voltages is ensured. The BJT device is adopted, and compared with a traditional CMOS transconductance circuit, the BJT transconductance circuit has lower noise and offset. By utilizing the source electrode degeneration and transconductance replication technology of input geminate transistors, constant transconductance can be maintained in a wider input voltage range, and high linearity can be maintained in a wide input range.

A microampere current detection system includes a solar panel, a battery pack, a voltage stabilizing circuit, an instrumentation amplifier, a sampling resistor, a microcontroller unit (MCU), and an XBee ® communication module. Two ends of the sampling resistor are connected to a sensor and convert current to voltage. The instrumentation amplifier outputs an amplified voltage signal. The MCU continuously acquires the voltage signal by using a hardware direct memory access (DMA) function of the MCU and obtains an analogue to digital converter (ADC) sampling value through digital filtering. The MCU calculates a current parameter value based on the ADC sampling value, compresses and encrypts the ADC sampling value and current parameter data. The MCU also sends a generated package to the communication module, and send the package data wirelessly via the communication module. Protocols such as 802.15.4 may be used.

The invention discloses a multi-path instrumentation amplifier which comprises a low-frequency amplification circuit and a high-frequency amplification circuit which are coupled between a voltage input end and a voltage output end. The high-frequency amplification circuit comprises a first amplifier, a second amplifier, a first input resistor, a first input capacitor, a second input resistor, a second input capacitor, a first feedback capacitor and a second feedback capacitor. The reverse output end and the non-reverse output end of the first amplifier are respectively coupled with the non-reverse input end and the reverse input end of the second amplifier, and the non-reverse output end and the reverse output end of the second amplifier are coupled with the voltage output end. The first feedback capacitor is coupled between the voltage output terminal and the inverting input terminal of the first amplifier. The second feedback capacitor is coupled between the voltage output terminal and the non-inverting input terminal of the first amplifier.

A fully integrated micro search coil magnetometer (μSCM) with a low-noise instrumentation amplifier is provided for low-frequency magnetic field measurements in the range of 1Hz to 1kHz. A micro search coil formed by stacking planar spiral inductors and serially connecting them with an in-phase configuration is used for magnetic field measurements. The critical line width and inner diameter of a planar spiral inductor are theoretically calculated and experimentally verified, enabling the development of a unique CMOS layout. This layout incorporates the calculated critical inner diameter, significantly optimizing the area utilization on the CMOS die. Additionally, the CMOS die includes a polysilicon-layer inductor for on-chip calibration, a Hall effect sensor for DC magnetic field measurement, and a temperature sensor for enhanced functionality. The μSCM delivers a compact, energy-efficient, and highly sensitive solution for low-frequency magnetic field measurements, surpassing the performance of most commercially available Hall effect sensors.

The present application relates to the technical field of electronic circuit, and especially relates to a readout circuit of a terahertz detection array, which comprises: a readout link at least comprising a current feedback instrumentation amplifier, a programmable gain amplifier and an incremental analog-to-digital converter connected in sequence; the current feedback instrumentation amplifier amplifies the signal output by the detector and outputs a first-stage amplified signal, the current feedback instrumentation amplifier comprises an instrumentation amplifier body and a first ripple suppression module, the first ripple suppression module comprises a first redundant segmented current steering DAC and a first DAC code register; the programmable gain amplifier further amplifies the first-stage amplified signal, the programmable gain amplifier comprises a gain amplifier body and a second ripple suppression module, and the second ripple suppression module comprises a second redundant segmented current steering DAC and a second DAC code register. The present application effectively reduces the chip area and power consumption while ensuring that the readout circuit of the terahertz detection array has high gain, low noise and low offset.

A kind of parallel machine current adding system belongs to the technical field of electronic equipment for measurement and testing, solve how to design a kind of hardware circuit simple, control precision high parallel machine current adding and system problem;The parallel machine current adding and system of the present application, comprising: multiple single machine current sampling circuits, parallel machine current adding and circuit;Single machine current sampling circuit includes: first differential amplifier circuit, first proportional regulating circuit, first unit inverter circuit, first digital potentiometer;Parallel machine current adding and circuit includes: instrument amplifier circuit, second proportional regulating circuit, second unit inverter circuit, second digital potentiometer and multiple proportional input end resistance;Digital potentiometer is applied to parallel machine circuit, and the resistance value of potentiometer is assigned by the number of parallel machine table set to realize the adjustment of amplification factor, replace the single proportional resistance resistance value of traditional resistance proportional circuit to realize the adjustment of amplification factor, hardware circuit is simple, amplification factor control is accurate.

In described embodiments, a sensor array comprising a plurality of resistive elements arranged in a plurality of rows and columns is provided. The row driving unit is configured to connect a plurality of rows of resistive elements of the sensor array to a voltage source for driving the voltage source to the row of resistive elements. The row driving unit also includes a switching unit for performing a switching operation, a row driving amplifier, and a feedback instrumentation amplifier (FBIA). Each of the switching units is selectively coupled to each of the row drive amplifiers, and each of the row drive amplifiers is further coupled to each of the plurality of FBIAs. A column scanning unit for detecting a voltage signal of a resistive element includes a column operational amplifier. Each of the column operational amplifiers is further connected to a column of the sensor array.

The utility model provides a temperature protection circuit. The temperature protection circuit comprises an instrument amplifier sub-circuit, a subtraction operation amplification sub-circuit, a cold junction compensation sub-circuit and a hysteresis comparator sub-circuit, the forward input end and the reverse input end of the instrument amplifier sub-circuit are used for receiving first voltage converted by the thermocouple; the subtraction operation amplification sub-circuit comprises a first operational amplifier, the output end of the instrument amplifier sub-circuit is connected with the reverse input end of the first operational amplifier, and the output end of the cold junction compensation sub-circuit is connected with the positive input end of the first operational amplifier; the hysteresis comparator sub-circuit comprises a second operational amplifier, the output end of the subtraction operation amplification sub-circuit is connected with the reverse input end of the second operational amplifier, the output end of the second operational amplifier is used for being connected with a switch, and the switch can switch the switch state according to an output signal of the second operational amplifier. According to the utility model, no extra space is occupied, and the set values of the protection temperature and the recovery temperature can be adjusted as required, thereby being more flexible.

The invention discloses a portable human heart imaging hardware system based on bioelectrical impedance. The system comprises an excitation signal processing module, a detection signal conditioning module and a digital processing module. The excitation signal processing module adopts a DAC (Digital-to-Analog Converter) to generate an excitation signal, and after voltage amplification and band-pass filtering, the excitation signal drives an excitation electrode through an analog switch; the detection signal conditioning module switches a measuring electrode through an analog switch, a programmable instrumentation amplifier is combined with an RDAC digital potentiometer to realize self-adaptive gain adjustment of a detection signal, flexible gain of the signal is realized, and the signal is sent to an ADC after being filtered; the digital processing module carries out digital demodulation on the collected signals, extracts amplitude and phase information and then transmits the amplitude and phase information to an upper computer for image reconstruction. The flexible signal gain mechanism of the system realizes a full-custom signal gain curve, breaks through the fixed magnification gain limitation of the traditional integrated PGA, adapts to the impedance change of different individuals and experimental media, and improves the signal-to-noise ratio of the system, thereby obtaining more accurate cardiac impedance acquisition data.