0.342 nW Class-AB enhanced flipped source follower low pass filter for biomedical applications

Abstract

Owing to the impact of process voltage and temperature variations, the design of low-power low-pass filters (LPFs) with improved linearity is still one of the most challenging tasks for effective biological signal processing. This paper presents the design of a fourth-order Class-AB enhanced flipped source follower (EFSF) LPF circuit aimed at the detection of electroencephalography signals. The simulated results attained using complementary metal–oxide–semiconductor 180 nm technology node in Cadence Analog Design Environment demonstrate that the EFSF LPF emulates a DC-gain of −88 mdB with a bandwidth of 100 Hz and consumes 0.342 nW power from a supply voltage of 0.5 V. The calculated figure of merit for the proposed filter is 5.983 × 10−15 J with a dynamic range (DR) of 43.54 dB and input-referred noise of 91 µVrms. It consumes an area of 0.0458 mm2. To check the robustness of the proposed filter circuit, we performed Monte Carlo simulations with 200 runs. The statistical results achieved for the DC-gain, DR, and total harmonic distortion of the proposed filter show mean values of −188.09 mdB, 43.10 dB, and −41.85 dB along with standard deviation values of 285.21 mdB, 718.72 mdB, and 4.52 dB, respectively. The proposed Class-AB EFSF LPF can be used to achieve high power efficiency in future low-voltage and low-power biological systems.