970302/746674/C/724 A Low Power Analog Front-end Module for Cochlear Implants

SUMMARY Front-end modules in current cochlear implant devices make use of parallel banks of independent bandpass filters. Compared to the earlier front-end modules implementing formant extraction, filter banks dissipate less power and have superior performance. To further improve the performance of such front-end modules, we propose a front-end module, which consists of a cascade of adaptive second-order filters, models of inner hair cells, and spectral feature-detection circuits. Compared to the existing front-end modules, the proposed front end reduces power dissipation by a factor of 20-100 because the MOS transistors in its circuits are operated in weak inversion. In addition, the module mimics aspects of the biological cochlea like broadening of place information with intensity, gain control, and sharp frequency roll-off slopes. The module can provide the phase information that is necessary for implementing phase-based coding strategies.