Flipped voltage follower based fourth order filter and its application to portable ECG acquisition system

This paper presents the designing of a compact flipped voltage follower (FVF) based fourth order low-pass filter (LPF). The circuit is designed by cascading current-reuse P-FVF and N-FVF biquads operating in sub-threshold region. The circuit attains a cut-off frequency of 206.14 Hz designed for portable ECG acquisition system. The proposed circuit is simulated in 0.13  μm CMOS technology in Cadence environment. The circuit occupies a chip area of 180.310  μm × 552.390  μm i.e. 0.0996 mm². LPF consumes 2.46 nW power with a supply voltage of 0.5 V. It provides a dynamic range of 65.17 dB with input referred noise of 22.214μVrms, HD₃ of 60.3 dB with 50 mVpp 50 Hz frequency. The circuit is compared with state of the art LPFs which provides the best figure of merit and shows enhanced performance in terms of noise, HD3 and dynamic range with lowest supply voltage and technology node.