A Chopper Stabilized Pre-amplifier for Biomedical Signal Acquisition

This paper presents a low-power and low-voltage pre-amplifier for biomedical signal acquisition application. The main blocks of the pre-amplifier consist of a chopper stabilized VGA, and a 4^th order filter. The amplifier serves to improve the noise figure at low frequency by extensively modulating the flicker noise to the 16 kHz chopper frequency. The filter is designed to strictly remove the modulated flicker noise and amplifier inherent offset with attenuation greater than 60 dB at the chopping frequency. Implemented in a 0.18-mum CMOS, the pre-amplifier achieves variable gain of 20, 40, and 100 V/V with an approximate noise density of 48.37 nV/radicHz and consumes 270 muA current.