A low-power polar demodulator for impedance spectroscopy based on a novel sampling scheme

This paper proposes a low-power polar demodulator for electrical impedance spectroscopy. The magnitude and phase of impedance are measured by a novel sampling scheme and an XOR-based scheme, respectively. The novel sampling scheme only requires switched capacitor circuits and clock signals that are already used in the analog-to-digital conversion and the phase measurement. Since the proposed demodulator does not require any additional circuits for the magnitude measurement, low power consumption and small die areas can be achieved. The proposed demodulator designed using a 0.18-μm CMOS process consumes about 10-mW average power with 0.23-mm² active area.