Analysis and Design of a Ripple Reduction Chopper Bandpass Amplifier

A low-power low-noise chopper amplifier for biosensor applications is proposed. To tackle the inherent ripple artifacts, it employs a simple ripple reduction method using a bandpass amplifier. The chopper amplifier is a linear periodic time-varying system. The method of harmonic transfer matrix is used to derive the signal and the noise harmonic transfer functions, and the theoretical results are confirmed by simulation and measurement results. Fabricated in a 130-nm standard CMOS process, the proof-of-concept prototype occupies a chip area of 0.28 mm
²
and consumes 3.3 μA from a 1.2-V supply. The input referred noise is only 43 nV/(Hz)
^1/2
.