Retinal prostheses require the presence of viable population of cells in the inner retina. Evaluations
of retina with Age-Related Macular Degeneration (AMD) and Retinitis Pigmentosa (RP)
have shown a large number of cells remain in the inner retina compared with the outer retina.
Therefore, vision loss caused by AMD and RP is potentially treatable with retinal prostheses.
Photostimulation based retinal prostheses have shown many advantages compared with retinal
implants. In contrary to electrode based stimulation, light does not require mechanical contact.
Therefore, the system can be completely external and not does have the power and degradation
problems of implanted devices. In addition, the stimulating point is
flexible and does not require
a prior decision on the stimulation location. Furthermore, a beam of light can be projected on
tissue with both temporal and spatial precision. This thesis aims at fi nding a feasible solution
to such a system.
Firstly, a prototype of an optoelectronic stimulator was proposed and implemented by using the
Xilinx Virtex-4 FPGA evaluation board. The platform was used to demonstrate the possibility
of photostimulation of the photosensitized neurons. Meanwhile, with the aim of developing
a portable retinal prosthesis, a system on chip (SoC) architecture was proposed and a wide
tuning range sinusoidal voltage-controlled oscillator (VCO) which is the pivotal component of
the system was designed. The VCO is based on a new designed Complementary Metal Oxide
Semiconductor (CMOS) Operational Transconductance Ampli er (OTA) which achieves a good
linearity over a wide tuning range. Both the OTA and the VCO were fabricated in the AMS
0.35 µm CMOS process. Finally a 9X9 CMOS image sensor with spiking pixels was designed.
Each pixel acts as an independent oscillator whose frequency is controlled by the incident light
intensity. The sensor was fabricated in the AMS 0.35 µm CMOS Opto Process. Experimental
validation and measured results are provided
