Current controlled CMOS stimulator with programmable pulse pattern for a retina implant

In this work the constant current stimulator of a new epiretinal implant is presented. It consists of a digital waveform generator device, which permits to modify the pulse pattern via a programming interface, a digital-to-current converter, which translates the digital waveform into current pulses with adjustable amplitude, and an output driver, which combines the function of an electrode multiplexer and a high voltage current source for driving large resistive loads. For each of those subcircuits the simulated performance and its designed layout is presented.