改进LCR仪表测量稳定性的相位裕度优化方法及硬件实现  

Phase margin optimization method and hardware realization to improve the measuring stability of LCR instrument

作　　者：杨学文 陈灵强 马凯元 Yang Xuewen;Chen Lingqiang;Ma Kaiyuan(School of Information and Electrical Engineering,Hebei University of Engineering,Handan 056038,China)

机构地区：[1]河北工程大学信息与电气工程学院,河北邯郸056038

出　　处：《电子技术应用》2024年第12期70-76,共7页Application of Electronic Technique

摘　　要：为解决LCR表在测量容性阻抗时的自激问题,设计了一种增强测量稳定性的LCR仪表。通过分析测量前端自平衡电桥电路的相位裕度,采用相位补偿电路解决因相位滞后造成的自激问题。应用直接数字频率合成技术结合相位校准电路设计,产生相位准确的正交测量信号。使用开关鉴相式锁相放大器处理微弱信号,经16位模数转换器采集后输入到微处理器进行矢量信号合成与输出显示。相比专业仪器,所设计样机对电阻测量相对误差可达0.5%,对大电容测量相对误差可达1%。To address the self-excitation issue in the measurement of capacitive impedance using LCR meters,an LCR instrument has been developed to enhance measurement stability.By analyzing the phase margin of the self-balancing bridge circuit at the measurement front-end,a phase compensation circuit has been employed to resolve the self-excitation problem caused by phase lag.Utilizing direct digital frequency synthesis combined with a phase calibration circuit design,quadrature measurement signals of accurate phase are generated.A switch-phase discriminator lock-in amplifier is used to process weak signals,which are sampled by a 16-bit analog-to-digital converter and input into the microprocessor for vector signal synthesis and output display.Compared to professional instruments,the prototype designed has achieved a relative error of up to 0.5%for resistance measure-ments and up to 1%for large capacitance measurements.

关 键 词：自平衡电桥 相位裕度 直接数字频率合成 锁相放大器 

分 类 号：TN98[电子电信—信息与通信工程]