Time-Based Wireless Synchronous Detection of Bioimpedance Signals

This letter presents a novel time-based scheme for wireless measurement of bioimpedance. Conventional circuits measure impedance in the analogue or digital domain, incurring in high power and area consumption resulting from either the use of analogue multipliers and high-order filters, or high-speed ADCs. Wireless transmission of impedance bits further results in a power penalty. Time domain solution offer a unique advantage both in terms of power consumption and technology scalability. Here we present a system that combines a pulse-width modulation–pulse position modulation readout with a pulse-harmonic modulation wireless link for power efficient transmission of impedance data. The paper presents a system-level description of the wireless readout architecture and its operation simulated in MATLAB/SIMULINK and LTSpice. The work presented here can provide the foundation for the design of novel time-based energy-efficient wireless impedance analysers.