Time-Constant Induced Memory Effect for Biomedical Radar Vital Signs Detection

Applications of Doppler radar for vital signs have been studied and investigated for a long time, and significant strides towards implementing Doppler radar sensors for such applications have been made in recent years. Designing optimum hardware component values for AC coupling and baseband signal amplification for radar sensing applications remains challenging. The selection of capacitor value for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$A C$</tex> coupling has a significant impact on the accuracy of small movement detection due to the memory effect induced by the time constant. In this paper, a study on the induced timeconstant memory issue on data due to intermittent shifts in signal from radar has been conducted, and analysis regarding the correct selection of capacitor values to mitigate the problem is proposed via simulation and verified by experimental analysis.