An on/off spiking photoreceptor for adaptive ultrafast/ultrawide dynamic range vision chips

In this work we present an adaptable spike generator circuit for intelligent vision chips. Our aim is to realize an adaptable vision chip which can adjust for localized gain control, wide dynamic range, high temporal response, high spatial resolution and low power. To this end we have developed pulse frequency modulation spike encoder which is capable of providing very high dynamic ranges with power consumption similar to animal retina. At lower dynamic ranges, frequency responses of over 2kHz is possible. Our circuit is based on the on-off opponency algorithm used by the human eye, and allows for integration of other functions such as tomographic increase in spatial resolution and information compression. Both silicon area and power consumption are kept to a minimum. This paper discusses the algorithm, its implementation and simulated results describing its response and power consumption.