Class - E Power Amplifier Design and Back - Telemetry Communication for Retinal Prosthesis

PUNDI, BHARATRAM SATYANARAYANAN. Class-E Power Amplifier Design and Back-Telemetry Communication for Retinal Prosthesis. (Under the direction of Wentai Liu.) This thesis discusses the power link in the retinal prosthesis project that aims to provide vision to the profoundly blind. Clinical experiments have confirmed that electrical stimulation can be used to duplicate the action of photoreceptors in the retina to provide vision to blind patients suffering from RP/AMD. The retinal prosthesis system consists of an intraocular unit implanted inside the eye and a separate extraocular unit. The microstimulator involved in retinal prosthesis consists of multiple electrodes arranged in twodimensional array and is a part of the intraocular unit. The micro-stimulator needs data and power to be transferred wirelessly from the extraocular unit. The power link consists of a highly efficient Class-E driver that transfers power inductively to the intraocular unit. A Class-E power driver is developed to suit the requirements and has been analyzed. The effect of the loaded Q variations on the Class-E circuit has been studied. Back-telemetry from the intraocular unit is necessary and is achieved through load modulation in the intraocular unit. A novel variation of PWM encoding has been conceived and employed to combine data and clock. The data detection unit consisting of an envelope detector and a PWM decoder has been developed. The data received is processed in the extraocular unit to adjust the power transfer and achieve power regulation. The format for data transmission has been proposed to arrange data into continuous packets, which includes error detection capabilities. CLASS-E POWER AMPLIFIER DESIGN AND BACK-TELEMETRY COMMUNICATION FOR RETINAL PROSTHESIS