CMOS dynamic retina

A new design of hardware implementation for a biological visual system using CMOS VLSI technology is presented. Our goal is to construct a silicon dynamic retina that generates in real time outputs corresponding directly to signals observed in the corresponding levels of biological retinas. It responds to both the intensity and the variations in the intensity of the incident light with time. It should be more reliable than previous silicon retinas, and less sensitive to variations in the device parameters, fabrication processes and temperature effects. The retina realization in this work is mimicking the biology by introducing the ganglion cell´s layer. The output of the retina is analogous to the output of the ganglion cells in the vertebrate retina. Its components operate well above the threshold voltage, and thus have a wide dynamic voltage and current ranges, hence increasing the reliability of the CMOS circuit to small variations in the component parameters due to fabrication processes or temperature effects. The retina itself is not capable of distinguishing the events except for emitting pulses, whose duration and frequencies depend on the intensity and the wave length of the incident light. The proposed retina is stable compared to previous VLSI implementations