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

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 50 /spl mu/W 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 1.27 /spl mu/Vrms. The current-mode DC rejection circuit can suppress up to /spl plusmn/11 mV of input DC pedestal caused by medical electrodes, as well as the DC offset of the IA. The IA is fabricated in a standard 0.35/spl mu/m CMOS technology with a core chip area of 0.7mm/sup 2/.