A Front-End stage for neural signal recording based on a sigma delta modulator

A new device for peripheral neural signals recording is presented. The designed system is composed by an analog and a digital part. The analog part, to be integrated on an implantable CMOS chip, is kept as simple as possible and hosts a low noise first order pre-amplifier/pre-filtering stage that provides a 46dB gain in the bandwidth 800Hz-7.2kHz and a 16-bit 3rd order sigma delta modulator. A highly selective band-pass filter is implemented into the digital domain, incorporated in the decimator block of the sigma-delta converter; in this way it is possible to reduce total area (which is 0.4mm 2 for a single input channel) and power consumption (250μW, single channel) in the integrated, implantable module. Simulation results prove the capability of the proposed system to record signals whose magnitude is in the order of tens of microvolts thanks to the low Input Referred Noise (IRN) of 2.4μV rms of the input stage.