Research On A New LCR Digital Bridge

The LCR digital bridge tester is widely used in the field of electronic component measurement.Currently,there are two types of LCR digital bridges used: desktop LCR digital bridges and handheld LCR digital bridges.The desktop LCR digital bridge exhibits high measurement accuracy,but due to its high power consumption and large volume,inconvenient carrying and operation,high requirements for the usage environment,and high price,it is difficult for ordinary users to accept.In contrast,handheld LCR digital bridges not only break free from the constraints of the environment,but are also convenient to carry,and have the advantages of high accuracy and multiple measurement frequencies.In addition,the handheld LCR digital bridge is much cheaper than the desktop,which makes it have a wide range of applications and higher development value.This article studies a new type of LCR digital bridge using the on chip system PSo C5(CY8C5588)chip developed by Cypress Corporation in the United States,which includes programmable analog and digital modules of a 32-bit ARM Cortex-M3 CPU processor.The measurement principle adopts the free axis method,and the measurement system includes single power supply circuit,microprocessor master control unit,DDS signal source generation circuit,low-pass filter circuit,bridge circuit,programmable gain amplifier circuit,phase sensitive detection circuit,A/D conversion circuit,OLED display screen circuit.The circuit construction and software programming are carried out in the development environment PSo C Creator.The integrated development environment of PSo C Creator has a graphical design editor,forming a unique and powerful hardware/software collaborative design environment.The analog and digital design modules in PSo C5 have high integration,which can simplify the circuit structure and reduce the volume.The innovation of this article lies in fully utilizing the configurable analog digital resources inside PSo C5 to implement each module in the entire measurement system.Compared with traditional digital bridges,this bridge achieves a true single-chip structure.All hardware circuits,including signal source circuit,bridge circuit and software implementation are carried out in the PSo C5 system on chip.The paper conducted in-depth research on the LCR digital bridge,providing a detailed introduction to the design principle of the hardware circuit and the implementation process of the software system.In response to the impact of errors on system measurement,a combination of hardware debugging and software compensation was used to reduce the impact.An open circuit short circuit compensation circuit model was established to eliminate the influence of residual,and a distributed capacitance analysis model was established to improve the measurement accuracy of the system.The new LCR digital bridge measuring instrument designed in this article has two equivalent methods: series and parallel,which can meet the requirements of conventional measurement.The basic measurement accuracy of the system is 0.3%,with three typical test frequencies of 100 Hz,1k Hz,and 10 k Hz,and a measurement range of R/Z: 0.1Ω～10MΩ;L:0.1μH～10H;C:1p F～1F。...