A High‐Stability Sub‐100 nW, First Order Tunable Gm−C Low‐Pass Filter With 5.7 Hz/V Line Voltage‐Sensitivity and 1.4 Hz/°C Thermal Drift

This paper presents a robust, ultra‐low‐power first‐order tunable low‐pass filter implemented in CMOS technology, specifically optimized for low‐frequency biomedical applications. Operating at a near‐threshold supply of , the proposed filter achieves a wide bandwidth tunability from to . To address the inherent instabilities of sub‐threshold operation, a novel circuit topology is employed that ensures bandwidth invariance against environmental and electrical fluctuations. Chip‐level post‐layout simulation results demonstrate an exceptionally low line sensitivity of over a wide supply range (0.5–3.0 V) and a temperature‐compensated sensitivity of only across a to range. The design maintains high signal integrity with a total harmonic distortion (THD) < 1 % for inputs up to , yielding a dynamic range. With an input‐referred noise density of and a total power consumption of only ( current drawn), the proposed filter offers a state‐of‐the‐art solution for energy‐constrained, reliable wearable healthcare monitoring systems.