32.2 A Stimulus-Scattering-Free Pixel-Sharing Sub-Retinal Prosthesis SoC with 35.8dB Dynamic Range Time-Based Photodiode Sensing and Per-Pixel Dynamic Voltage Scaling

Retinal prosthesis (RP) systems-on-chip (SoC) for the treatment of age-related macular degeneration (AMD) and retinal pigment degeneration have been widely studied for restoring visual function. RP SoCs allow the brain to perceive visual information by applying current stimuli to the retinal cells. An epi-retinal prosthesis (epi-RP) obtains image information from an external camera and provides appropriate stimuli to the ganglion cells [1]. On the other hand, a sub-retinal prosthesis (sub-RP) uses photodiodes (PD) to directly recognize light and stimulate bipolar cells [2]. Although the sub-RP SoC has potential to restore the patient's vision without bulky external devices, it suffers from three major problems that limit the functionality and safety.