Retina Stimulator with Channel Dependent Arbitrary Waveforms in 28nm CMOS Process

Many concepts for retinal prostheses rely on biphasic pulses for stimulation, although studies suggest alternative waveforms might improve visual perception. This paper presents a highly flexible retina stimulator using a 28 nm CMOS process. Each driver can provide an arbitrary waveform for stimulation, independently from other channels. The type of stimulation can be switched between voltage and current mode. An inter-channel stimulation approach is proposed which delivers reasonable stimulation levels of up to ± 1.8V, even with such a small technology node. The implementation of a channel is presented along with two different digital approaches of waveform generation. Area and power consumption of the driver are investigated. Measurement results verify correct operation.