A CMOS adaptive interference reduction system for nerve cuff recordings

This paper describes the realisation of an automatic control system for use in nerve cuff recordings. The system compensates for any impedance mismatches in the cuff by adaptively adjusting the gains of the input differential amplifiers connected to the cuff electrodes. As a result, interference pick-up during nerve recordings is greatly reduced. The gains of the variable gain amplifiers are adjusted by means of current feedback. The control chip was fabricated in 0.8µm CMOS technology, has a core area of 0.35mm²and consumes 3.5mW from ±2.5V power supplies.