Design of Retinal Ganglion and Bipolar Cell Exhibiting Near Biological Response

Neuromorphic engineering is multidisciplinary branch of biology, physics, mathematics, neuroscience, electronics engineering and computer science. Neuroscientists are working on mimicking retina, cochlea, motoring neurons etc. For the retinal systems, substantial research has been done due to which understanding of basic components, connection methods and computational processes becomes easier. There are various approaches like mathematical modeling, device modeling, circuit level and system level modeling by which retina can be mimicked. Still researchers get new challenging tasks due to new insights given by neuroscientists into retinal biological system. Due to adaptive nature of human brain, modeling of neurons and synapses is a challenging task. Generally, area, speed and power are the major tradeoffs in any VLSI (Very Large Scale Integration) circuits; however, degree of biological realism and robustness need to be considered in neuromorphic circuits. There are many research papers available in the literature related to modeling of bipolar and ganglion cells, however circuits giving near biological response are the most sought-after circuits. In this paper, spiking behaviour of combined bipolar and ganglion cell is mimicked considering novel averaging and multiplier circuit for bipolar cell, and comparator-based circuit for ganglion cell to mimic the best possible near-biological response. The circuit is implemented using TSMC 180nm technology using LTSpice.