ABSTRACT
The retina is often referred to as an approachable part of the brain and is composed of exquisite neural circuitry that performs an amazing level of processing. There are two diseases that affect only the sensory transduction layer, the photoreceptor layer, of the retina. The first is age-related macular degeneration (AMD) and the second is retinitis pigmentosa; both these diseases result in a loss of photoreceptors. The goal of an artificial retinal prosthesis is to stimulate the remaining healthy layers of retinal neurons using brief biphasic pulses of current. These current pulses produce a sensation of vision in the brain that is termed a phosphene. This chapter provides the basic architecture of the stimulator chip. The chip is powered via an inductive link; the power signal is rectified and filtered using off-chip diodes and capacitors with the nominal supply voltage being ±2.5 V. The digital data are transmitted using an amplitude shift keyed (ASK) waveform.
