A 1.1uW 2.1uVrms Input Noise Chopper Amplifier for Biomedical Applications

Abstract

Micropower amplifiers for neural sensing and other biosignals are becoming increasingly relevant in cutting edge biomedical research. This thesis presents a complete 1.1uW two stage subthreshold low-noise amplifier configured for measuring local field potentials (brain signals used in neuroprosthetics). The first stage chopper amplifier is a 700nW folded cascode topology with three low-impedance node mixers that allow different sections of the amplifier to be chopped at different frequencies for lower noise levels. With a simulated NEF (noise efficiency factor) of 3.28 the first stage amplifier has the potential for incorporating many recording channels on an implanted IC; making efficient use of both silicon area and battery power.