A Multi-channel Low-power Circuit for Implantable Auditory Neural Recording Microsystems

A multi-channel low-power circuit for auditory neural signal processing from multichannel microprobes for implanting in the auditory nerve has been designed and simulated. The chip is being fabricated with the AMI 0.5 μm triple-metal double-poly CMOS process with a die size of 1.5 × 1.5 mm. Low-noise and low-power preamplifiers are designed to pick up the weak signals from each microelectrode with a gain of 36 dB, bandwidth from 5 Hz to 7.2 kHz, and a power consumption of 98 μW. Analog time division multiplexers (MUX) are used for each group of eight electrodes to conserve external leads and discriminate signals from different recording sites with a power dissipation of 0.04 μW per multiplexer. An 8-bit successive approximation Analog-to-Digital Converter (ADC) is designed to digitize the analog signals. The ADC consumes 0.84 μW at 1.5 V supply with a sampling rate 100 kS/s. The overall power dissipation per channel is less than 100 μW.