Amplitude and Phase Errors Optimization for High-Precision Electrical Impedance Measurement System

Due to its non-invasive, deep sensing and radiationfree characteristics, electrical impedance measurement has become a key technique in empowering biological imaging and flexible sensing applications. However, large amplitude error and phase errors exist in conventional electrical impedance measurement system due to the harmonic error of demodulation and the limited bandwidth of the circuit, which will significantly affect the accuracy of the flexible sensing systems. A system level low amplitude and phase error optimization scheme is proposed with amplitude correction and pre-I/Q-demodulation. Behavior model is built to verify the error reduction of the proposed scheme. For the electrical impedance tomography application, behavior model simulation shows that the impedance is measured with 0.45% amplitude error and 0° phase error. Compared to the conventional system, the proposed scheme achieves a $\mathbf{7 4 \%}$ reduction of amplitude error and a 100% reduction of phase error.