An Integrated System for Multichannel Neuronal Recording with Spike / LFP Separation and Digital Output

A mixed-signal front-end processor for multichannel neuronal recording is described. It receives twelve differential-input channels of implanted recording electrodes. A programmable cutoff HPF blocks DC and low frequency input drift. The signals are band-split at about 200 Hz to low frequency local field potential (LFP) and high-frequency spike data (SPK), which is band limited by a programmable-cutoff LPF. Amplifier offsets are compensated by calibration DACs. The SPK and LFP channels provide variable amplification rates of up to 5000 and 500, respectively. The analog signals are converted into digital form, and streamed out over a serial digital bus. A threshold filter supresses inactive portions of the signal and emits only spike segments. A prototype has been fabricated on a 0.35/mum CMOS process and tested successfully