Biography
Enrollment Date: 2005
Graduation Date：2007
Degree：M.S.
Defense Date：2007.12.17
Advisors：Chun Zhang
Department：Institute of Microelectronics，Tsinghua University
Title of Dissertation/Thesis：Design and Implementation of Filter Banks for Cochlear Implant
Abstract:
The profoundly deaf patients cannot resort to the hearing aid device, however, through cochlear implant, which is proved to be effective, it is completely possible for them to restore hearing. Cochlear implant can deliver electrical stimulus to auditory nerve directly, to provide the sensation of sound to those who are profoundly deaf. It is a progeny of the combination of neurophysiology, psychology and electronics. Digital multi-channel cochlear implants have been widely used since early 80's last century, and are now advancing towards fully or semi implant solutions. This thesis bases its work on the DSP core of our research group, namely the low power implant DSP prototype — CISP (Cochlear Implant DSP). The purpose of this work is to provide the speech coding strategies for the implanted DSP processor. CIS (Continuous Interleaved Sampling) class strategy is one of the predominant algorithms applied by current leading foreign companies. In this thesis, a CIS strategy is carried out, and the assembler code is compiled into binary machines’ code, to be used by CIDSP core as testing vectors. CIDSP is standard-cell based, and is designed following the ASIC design flow. After the design verification and careful back-end design, CIDSP prototype is taped out using UMC 0.18um 1P6M RF process, taking advantage of standard-cell library, I/O pads library and SRAM library from Artisan Company. The band pass filter bank of CIS class strategies is further discussed. A wavelet packet filter bank prototype is designed and implanted on CIDSP, to improve the non-stationary speech signal processing effect of the system. A deep going study is carried out to the wavelet packet filter bank, the key processing unit of the assemble program is designed into an ASIC module. This module reduces the time frequency of the real-time system into its half. And the power consumption is thus reduced. All the strategies implemented in this work are not limited to the processor implanted cochlear implant system, they can also be used or referenced by all the other digital multi-channel cochlear implant system with a speech processor outside the human body.