SoC for retinal ganglion cell stimulation with integrated sinusoidal kilohertz frequency waveform generation

For retinal prostheses strategies to increase the stimulative cell selectivity are required to generate neural responses to electrical stimulation of retinal ganglion cells (RGCs) that match the response of the natural signal pathway. An important part of these strategies is the modulation of stimulus amplitude and frequency in the kilohertz range. The aim of this research is to investigate the electronic challenges and requirements of new electrical stimulation strategies for future retinal implants. This paper presents a 42 channel current controlled stimulator which is able to stimulate retinal tissue with sinusoidal frequencies higher than 1 kHz at amplitudes of up to 200 μA. The power efficiency of the stimulator is 87.3% at a supply voltage of 1.8 V. One stimulator requires a respective area of 0.0071 mm2 by using a 180 nm CMOS technology.