An Advanced Low Power and Versatile CMOS Current Driver for Multi-Electrode Cochlear Implant Microstimulator

摘要

We present in this paper an advanced and versatile CMOS current driver to be used in one sixteen electrode cochlear implant microstimulator that was dedicated to flexible and programmable stimulation. The overall targeted ASIC circuit would be versatile and totally numerical in order to achieve a high degree of programmability for cochlea's electrical stimulation. It could be adapted to any other external part of one cochlear prosthesis 'the sound analyser' that could be driven by a digital signal processor 'DSP.' We focused our attention in this research to the electronic stimulation stage since it was very important part for this biomedical device. Electronic circuit conception was then built around a digital controller stage piloting another analogue stimulation stage. The main internal functions assured during digital processing permitted to determine with great flexibility stimuli parameters (stimulation current level and width, stimuli rhythm) to generate at each specified channel. Our implantable designed microchip which involves electrical stimulation to the auditory nerve fibbers includes an advanced low power and versatile CMOS current driver. Originality provided in such stimuli generation concerns numerical current level ranging around ±1 mA with 10-bit resolution, the ～30 MΩ output impedance as well as numerical current pulse width. Microelectronic design of this biomedical device was based on the specific following technology: the AMI 0.35 μm, 3-metal, 2-poly, n-well standard CMOS process. Based on this conception, and by using 3.3 V supply, the maximum power consumption was estimated to 1.41 mW and the chip size was evaluated to 0.09 mm{sup}2.