Abstract:

This brief presents a vital-sign processing circuit for simultaneous dc/near-dc elimination and out-of-band interference rejection without any digital signal processing or algorithm assistance for the ultra wideband (UWB) pulse-based radar system. An intrinsic self balanced MOS diode (SBMD) was proposed as a stable and balanced pseudo resistor applied under a servo feedback loop in a vital-sign receiver of the sensing radar to perform as a high-pass filter (HPF) with an ultralow corner frequency lower than 0.5 Hz for removing undesired clutters of the reflected signals and input dc-offset voltages from innate circuit offsets. A third-order switched-capacitor (SC) Chebyshev low-pass filter (LPF) with leap-frog topology as the subsequent stage was adopted to suppress the out-band noises, thereby establishing an integrated vital-sign processing circuit with band pass frequency response and incorporating it into a radar module to verify its viability.