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A 6 µW per Channel Analog Biomimetic Cochlear Implant Processor Filterbank Architecture With Across Channels AGC

Guang Wang
Emmanuel M. Drakakis
IEEE Transactions on Biomedical Circuits and Systems, vol. 9 (2015), pp. 72-86


A new analog cochlear implant processor filterbank architecture of increased biofidelity, enhanced across-channel contrast and very low power consumption has been designed and prototyped. Each channel implements a biomimetic, asymmetric bandpass-like One-Zero-Gammatone-Filter (OZGF) transfer function, using class-AB log-domain techniques. Each channel's quality factor and suppression are controlled by means of a new low power Automatic Gain Control (AGC) scheme which is coupled across the neighboring channels and emulates lateral inhibition (LI) phenomena in the auditory system. Detailed measurements from a five-channel silicon IC prototype fabricated in a 0.35 µm AMS technology confirm the operation of the coupled AGC scheme and its ability to enhance contrast among channel outputs. The prototype is characterized by an input dynamic range of 92 dB while consuming only 28 µW of power in total ~6 µW per channel) under a 1.8 V power supply. The architecture is well-suited for fully-implantable cochlear implants.