A low-voltage low-noise CMOS instrumentation amplifier for portable medical monitoring systems

Abstract

This paper presents a low voltage low noise CMOS instrumentation amplifier (IA) suitable for portable health monitoring devices such as electrocardiogram (ECG) and electroencephalogram (EEG). Based on a current-mode topology, the IA is able to operate under a 1-V supply and consumes 50μW while providing a voltage gain of 150. An optimum trade-off between noise and voltage headroom is obtained by choosing appropriate operating points and sizes of transistors. The measured input referred noise integrated from 0.4Hz to 200Hz is 1.27μVrms. The current-mode DC rejection circuit can suppress up to ±11mV of input DC pedestal caused by medical electrodes, as well as the DC offset of the IA. The IA is fabricated in a standard 0.35μm CMOS technology with a core chip area of 0.7mm2. © 2005 IEEE.