Modelling and design of asynchronous receptive circuit for cone pathways

Abstract

In this paper, asynchronous receptive circuit of retinal pathway is proposed for cone cells. Cone cells respond differently to different wavelengths of light and they are responsible for color vision. The cells present in retinal pathway namely cone photoreceptor, bipolar cell, amacrine cell and ganglion cell are mimicked using 180 nm Complementary Metal Oxide Semiconductor (CMOS) technology in strong inversion region. The proposed circuit is event based and hence asynchronous in nature. Additionally, amacrine stage is mimicked such that analog multiplexing occurs which is matching with its biological behavior. Both these features give output near to response of actual biological retinal pathway. The circuit detects wavelengths in visible spectrum of light with temporal contrast. At amacrine stage, selectivity is achieved without any external control signal which shows intelligent behavior at analog circuit level. The concept of color sensitivity of cone is considered to generate input stimulus of the circuit using Commission on Illumination (CIE) standard. The power consumed by the entire pathway circuit is 183 mW.