Research of Impedance Measurement System based on Adaptive Feedback Calibration Method

A portable measuring instrument based on micro-controller is designed in this paper. An impedance conversion chip AD5933 featured as high precision is considered to be the measuring sensor. A switch array consisting of micro-relays and high-precision resistors is devised to carry out system calibrating and range switching automatically by proposed adaptive feedback calibration approach. The test results show that the system presents satisfied accuracy and good stability with SNR 72.8 dB within $1\sim 100kHz$ and lower relative measurement error to 0.54% o within $ 0.02\sim 200k\Omega$. The measuring results of a complex circuit is verified to be coincide with the ideal curve. This paper provides an innovative method for fast and stable impedance measurement.