Implementation of Cochlear Implant Receiver Stimulator IC

Cochlear Implant consists of external body worn speech processor, transcutaneous inductive link and receiver stimulator. This paper describes the design of Bio-Implantable ASIC for a battery-less receiver stimulator. The IC demands low power consumption with a voltage compliance for high intensity current stimulus for wide electrode impedance upto 10KΩ with 1 mA of stimulus. The IC consists of power, data and clock recovery circuits, digital controller logic, data converters, charge pump and switch array matrix for stimulating electrodes. The Charge pump is designed to provide a programmable voltage boost from the internally recovered voltage of 1.8 V to 12 V in step of 1.2 V with 98% conversion efficiency. The boosted voltage acts as a high voltage supply to the electrode switch matrix. The ASIC is fabricated in 0.18μm power management CMOS technology and consumes a power of 6mW. This ASIC is assembled in a RoHS compliant implantable board of size 14 mm ×19.1 mm. This implant board is integrated with CI system and tested with 12 electrodes.