Highly programmable digital controller for high-density epi-retinal prosthesis

This paper presents the analysis and circuit design of a digital controller supporting up to 1024-pixel epi-retinal prosthesis. High programmability of each stimulation pixel is desirable to support various physiological conditions. The goal of this design is to achieve high programmability with limited wireless transmission bandwidth. Two-tier architecture is adopted to reduce chip area. Several circuit blocks are developed in this design: on-chip address generator (OCAG) and configuration mode reduce the data bandwidth requirement by 54.7%; flexible data parser enables the optimization between data discard rate and maximum frame rate; delay timer makes any scanning pattern possible. Multi-clock domain and data gating design are used to reduce power. A prototype 256 pixels epi-retinal prosthesis controlled by the proposed digital controller is fabricated in a 0.18mum CMOS HV technology. This digital controller can be used in other implantable multi-channel stimulation systems.