A 51fA/Hz0.5 low power heterodyne impedance analyzer for electrochemical impedance spectroscopy

摘要

This paper presents the design of a low-power highly sensitive impedance analyzer for electrochemical impedance spectroscopy (EIS) in a 0.18µm CMOS process. The analyzer uses a low-power current buffer with high gain to suppress the noise from the back-end. A heterodyne mixer is designed to reduce the flicker noise of following stages. It also enables the simultaneous recording of the amplitude and phase information. Experiments show it enables GΩ impedance sensing up to 100kHz with 51fA/Hz0.5noise and 89µW power.