A 2.2/spl mu/W 94nV//spl radic/Hz, Chopper-Stabilized Instrumentation Amplifier for EEG Detection in Chronic Implants

A chopper-stabilized instrumentation amplifier is targeted for "deep-brain" human implants and consumes 2.2muW from a 1.8V supply. The integrated noise from 0.5 to 100 Hz is 0.94muV, providing a noise efficiency factor of 4.9. The use of chopper stabilization provides rail-to-rail inputs and 105dB CMRR. An integrated 0.5Hz HPF is used to suppress electrode offsets. The circuit is also used in micropower bridge interfaces for impedance measurement and pressure sensing.