Design Of Portable RLC Measuring Instrument Based On FPGA

In digital integrated circuit and microprocessor highly development today, the traditionaltest method is no longer adapt to the trend, based on microprocessor and integrated circuitdesign of measurement instruments to arises at the historic moment.Traditional measuringprinciple and design thought is presented in this paper, on the basis of choosing theappropriate part of the improvement and innovation, introduced and applied to a practical,convenient and fast method to design the portable measuring instrument for measuringcomponents parameters. Using FPGA of high-speed, highly integrated and flexible andconvenient designing digital systems, will be used for the control of this system and dataprocessing circuit design, and design the corresponding data processing algorithm, make itmeet the requirements of system performance and portability.Design system by excitation signal source, the front-end measuring circuit, gear switchcircuit, high-speed A/D sampling, phase-sensitive detector, keyboard and LCD, etc. In thedesign of excitation signal source, the use of FPGA and external D/A conversion circuit,generating accurate measurement of frequency signal and clock frequency of the A/Dconverter signal. Front end by multistage gear measurement circuit of standard resistance andhigh precision broadband operational amplifier, can automatically select the correspondingmeasuring gear, complete range of automatic conversion, as well as to the signal amplificationcontrol, make small impedance measurement precision can be obtained in the process ofsampling signal. System USES digital phase detecting technology with high speed and highprecision A/D converter, instead of traditional double integral A/D sampling, the data will becollected by the digital filter and digital processing, in order to get more accuratemeasurements.This article detailed introduces the system hardware design and software algorithmmainly principle and implementation process, and on the basis of measured data, the erroranalysis and calibration software and hardware. Final system with high precision, portable,fast speed, etc, you can easily measure the value of the resistor, capacitor, inductor and related auxiliary variables such as the phase Angle theta and loss factor D, quality factor Q, etc.