A 1.2-µW 41-dB Ripple Attenuation Chopper Amplifier Using Auto-Zero Offset Cancelation Loop for Area-Efficient Biopotential Sensing

Abstract

In this paper, a low-power and low-noise capacitive-coupled chopper instrumentation amplifier (CCIA) is proposed for biopotential sensing applications. A chopping technique is applied to mitigate the domination of flicker noise at low frequency. A new offset cancellation loop is also used to deal with the intrinsic offset, originating from process variation, to reduce ripple noise at the output of CCIA. Moreover, the optimization of the chip area was resolved by adding a T-network capacitor in the negative feedback loop. The CCIA is designed on 0.18 µm process CMOS technology with a total chip area of 0.09 mm2. The post-simulation results show that the proposed architecture can attenuate the output ripple up to 41 dB with a closed-loop gain of 40 dB and up to 800 Hz of bandwidth. The integrated input referred noise (IRN) of the CCIA is 1.8 µVrms over a bandwidth of 200 Hz. A noise efficiency factor (NEF) of 5.4 is obtained with a total power dissipation of 1.2 µW and a supply voltage of 1 V, corresponding to a power efficiency factor of 9.7 that is comparable with that of state-of-the-art studies.