A Floating Point LMS based Automatic Balancing AC Bridge for BIS

Zhou Zhou, Hui Xu, Hongqi Yu, Xin Xu, Zhaolin Sun, Sen Liu, and Nan Li


Bioelectrical impedance spectroscopy, Digital automatic balancing bridge, Floating Point, LMS


A high precision automatic balancing AC bridge for bioelectrical impedance spectroscopy (BIS) is proposed in this paper. We introduce a FPGA compliant floating point least mean square (LMS) algorithm to improve the convergence and measurement performance of the bridge for BIS. Firstly, the principle of the LMS based bridge was described in detail. The floating point format is customized to adapt the FPGA specific multiplier fabric and guarantee calculation accuracy. We analyzed and evaluated the convergence performance of the floating point system by comparing with fixed point system. The measurement accuracy of our system for BIS is tested by introducing a commercial system and a fixed system as reference. The results show that proposed system has high convergence and measurement accuracy than traditional fixed point system. Our system is precise, fast and stable and offers benefits for BIS applications.

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