A variable range Bi-phasic current stimulus driver circuitry for an implantable retinal prosthetic device

Mohanasankar Sivaprakasam, Mark S. Humayun, Wentai Liu, James D. Weiland

Research output: Contribution to journalArticlepeer-review

131 Citations (Scopus)

Abstract

This paper reports a driver circuitry to generate bi-phasic (anodic and cathodic) current pulses for stimulating the retinal layer through electrodes which is part of a retinal prosthetic device for implants in blind patients affected by retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Dual voltage architecture is used to halve the number of interface leads from the chip to the stimulation sites compared to a single voltage supply. The driver circuitry is designed to deliver currents with six bit resolution for a wide range of full scale currents up to 600 μA. To cater to the varying stimulus requirements among patients and different regions of the retina, variable gain architecture is used to achieve fine resolution even for a narrow range of stimulus. 1:8 demultiplexing feature is embedded within the output stage thus allowing one DAC for eight outputs. A novel charge cancellation circuitry with current limiting capability is implemented to discharge the electrodes for medical safety. Measurement results of a prototype chip fabricated in 1.5-μm CMOS technology are presented.

Original languageEnglish
Pages (from-to)763-770
Number of pages8
JournalIEEE Journal of Solid-State Circuits
Volume40
Issue number3
DOIs
Publication statusPublished - 2005 Mar

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering

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