A multi channel chopper modulated neural recording system

Abstract

Presented herein is a fully integrated low-noise CMOS multi-channel amplifier for neural recording applications. The circuit employs the chopper modulation technique to reduce the effect of flicker noise and DC offset. A reduced area design implementation is achieved by trading off the increased noise margin performance of the chopper modulator for minimal amplifier area and analog multiplexing of the recording sites. A fully differential topology is used for the signal path to improve noise immunity. The analog amplifier exhibits 56 dB of gain with a 115 kHz bandwidth and a common mode rejection ratio (CNIRR) of 80 dB. Simulation results show a total input referred noise less than 16 nV/rootHz. The system power consumption is approximately 750 muWatts. The fully integrated system was designed in ABN 1.6-um single poly n-well CMOS process.