The Research And Design Of LCR Meter Based On CPLD Control

Resistor, capacitor, inductor, transformer is the most commonly used components of electronic equipment. Their performance is extremely important to instrument's precision. Therefor, the LCR meter is the most important instrument to electronic testing. Along with the rapid developement of Chinese industry, the requirement of the range, speed, acurancy and analyse function of the LCR meter has significantly increased.This paper describes a design about ARM, CPLD, and DDS technology. Based on the LCR meter theory, this paper did a research on the software and hardware design to improve testing bandwidth, range, speed and acurancy. The whole system consists of signal source module, voltage & current detection module, digital process module and etc. The signal source module provides DC to 500K Hz sine wave, range from 10mV to 2 V along with 1 OmA to 1A circuit source, based on DDS technology using CPLD controller. Phase detection circuit calculates the phase difference of two sine wave uing multi-slope analog-to-digital technology. Digital processing uses S3C6410 chip to achieve digital filter, vector decomposition, multiple parameter transformation functoin. In error compensation part, this paper builds a model about coupling impedance of the measurement channals. And the stability of the system is vertified based on a large number of experimental analysis.This paper is divided into six chapters:Chapter ? introduces the application background, basic principles of LCR meters, and compares the performance and the capacity of LCR meters from different companies, advantages and disadvantages of different methods.Chapter ? describes the overall design scheme, and analyses system requirements, provides solutions.Chapter ? introduces the hardware design of the system, combined with the principle, function, and device-selection analysis.Chapter ? introduces the software design, including the CPLD software design (verilog) and the host controller software design (C++). Also analyses the system error and provides a variety of compensation solutions.Chapter ? analyses measurement data and the problems happened in debugging, and provide theoretical solutions.Chapter ? summarize this projectThe prototype of the LCR meter is accomplished and the measurement indicators have reached the enterprise's technical specifications.