VLSI implementation of receptive fields with current-mode signal processing for smart vision sensors

Most of the early vision processes in vertebrate vision systems can be modelled by receptive fields in the retina. Building silicon retina ICs has been attempted in the past, but they have not reached a satisfactory conclusion due to technology constraints. Targeting a wafer-size smart vision sensor, we focus in this paper on researching the VLSI implementation of different receptive fields with dedicated functions. The microelectronic receptive field (MERF) is defined as a functional block of the larger system, performing a preprogrammed operation on visual input signals. The main component of MERF's are analog processors operating in current domain that use current signals from photodetectors to produce desired image processing function and to convert their outputs into frequency mode signals. Results from VLSI chips with various integrated implementations of receptive fields are presented.