A 15-Channel Wireless Neural Recording System Based on Time Division Multiplexing of Pulse Width Modulated Signals

Abstract

This paper describes a 15-channel wireless implantable neural recording (WINeR) system for long-term in vivo experiments. WINeRS consists of an implantable part that contains a system-on-a-chip (SoC) application-specific integrated circuit (ASIC) and an external receiver. The 3 mmtimes3 mm ASIC is fabricated in the MOSIS AMI 0.5-mum 3-poly 3-metal n-well standard CMOS process. The chip contains 15 low-noise amplifier/filters, time division multiplexer (TDM), sample-and-hold (S&H), pulse width modulator (PWM), on-chip clock generator, 32-bit register for control commands, ISM-band VCO transmitter, reference generator, and inductive power management circuitry. The use of PWM technique has lowered power consumption, improved robustness against noise, and reduced complexity by eliminating ADC and its associated circuitry. A commercial FM receiver is used as the external part of the system. The received PWM signal is further demodulated off-line by a MATLAB program. Finally by time division demultiplexing the demodulated samples, the original neural signals are being reconstructed. A custom wideband receiver with real-time PWM/TDM demodulator/demultiplexer is currently under construction