An auto-zeroing chopper-stabilized capacitively coupled instrumentation amplifier with 25-Vpp common-mode interference tolerance

Abstract

In this paper, an Electrocardiogram (ECG) signal amplifier with beyond supply rail common-mode interference (CMI) cancellation (CMIC) capability is proposed. The amplifier is composed of a comparator logic, a current source charge pump (CSCP), input pre-charge buffers, and an auto-zeroing (AZ) capacitively coupled chopper instrumentation amplifier (CCIA). The principle and circuit details of the CMI suppression circuit will be analyzed in the article. Based on a standard 180 nm CMOS process, it achieves a 25 $V_{\text{pp}}$ power line CMI tolerance from a 1.8-V supply. At an input CMI of 4 $V_{\text{pp}}$, it consumes 151.91 $\mu$W, achieves a total harmonic distortion (THD) of -78.8 dB, and has an effective number of bits (ENOB) of 12.02 bits.