Low-power filter design using quasi-floating gate and level shifter approaches for biological healthcare applications

Abstract

This paper proposes a 4th-order class-AB low-pass filter (LPF) for wearable biological healthcare applications designed by cascading two 2nd-order LPFs. The proposed class-AB LPF uses quasi-floating gate (QFG), flipped source follower (FSF) and level-shifter (LS) techniques to boost its performance. The LPF is designed and validated in CMOS 180 nm technology which emulates the post-layout gain of −0.212 dB, bandwidth of 100 Hz, dynamic range (DR) of 50.26 dB, total harmonic distortion (THD) of −52.5 dB and figure of merit (FOM) of 1.71 × 10-15 J. The class-AB QFG FSF LPF consumes power and area of 0.224 nW and 0.0196 mm2, respectively. Furthermore, the statistically determined coefficient of variation for proposed LPF with 1000 iterations for gain is −0.035, THD is −0.172 and DR is 0.04, respectively. The class-AB QFG FSF LPF is compared with other LPFs which establishes its advantage in terms of low-power consumption and least figure of merit thus confirming its suitability for wearable healthcare applications.