A fully-integrated bandpass amplifier for extracellular neural recording

This paper describes a fully-integrated bandpass amplifier for neural recording applications. Diode-connected sub-threshold-biased NMOS transistors in the feedback loop of the amplifier realize the high on-chip impedance necessary to eliminate the dc baseline potential of the electrode while amplifying neural field and action potentials. The amplifier has an in-band gain of 38.2dB, a dc gain of 0, an upper cutoff frequency of 24kHz and a low frequency cutoff of 66mHz. It consumes 92/spl mu/W from /spl plusmn/1.5V supplies and has an input-referred noise of 16.6/spl mu/Vrms integrated from 100Hz-10kHz. The amplifier occupies 0.082mm/sup 2/ in 3/spl mu/m features and is being used on a 64-site neural recording probe.