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Proceedings Paper

Programmable retinal dynamics in a CMOS mixed-signal array processor chip
Author(s): Ricardo A. Carmona; Francisco Jose Jimenez-Garrido; Rafael Dominguez-Castro; Servando Espejo; Angel Rodriguez-Vazquez
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Paper Abstract

The retina is responsible of the treatment of visual information at early stages. Visual stimuli generate patterns of activity that are transmitted through its layered structure up to the ganglion cells that interface it to the optical nerve. In this trip of micrometers, information is sustained by continuous signals that interact in excitatory and inhibitory ways. This low-level processing compresses the relevant information of the images to a manageable size. The behavior of the more external layers of the biological retina has been successfully modelled within the Cellular Neural Network framework. Interactions between cells are realized on a local basic. Each cell interacts with its nearest neighbors and every cell in the same layer follows the same interconnection pattern. Intra- and inter-layer interactions are continuous in magnitude and time. The evolution of the network can be described by a set of coupled nonlinear differential equations. A mixed-signal VLSI implementation of focal-plane low-level image processing based upon this biological model constitutes a feasible and cost effective alternative to conventional digital processing in real-time applications. A CMOS Programmable Array Processor prototype chip has been designed and fabricated in a standard technology. It has been successfully tested, validating the proposed design techniques. The integrated system consists of a network of 2 coupled layers, containing 32×32 elementary processors, running at different time constants. Involved image processing algorithms can be programmed on this chip by tuning the appropriate interconnection weights, internally coded as analog but programmed via a digital interface. Propagative, active wave phenomena and retina-lake effects can be observed in this chip. Low-level image processing tasks for early vision applications can be developed based on these high-order dynamics.

Paper Details

Date Published: 18 April 2003
PDF: 11 pages
Proc. SPIE 5119, Bioengineered and Bioinspired Systems, (18 April 2003); doi: 10.1117/12.499013
Show Author Affiliations
Ricardo A. Carmona, Univ. de Sevilla (Spain)
Ctr. Nacional de Microelectronica (Spain)
Francisco Jose Jimenez-Garrido, Univ. de Sevilla (Spain)
Ctr. Nacional de Microelectronica (Spain)
Rafael Dominguez-Castro, Univ. de Sevilla (Spain)
Ctr. Nacional de Microelectronica (Spain)
Servando Espejo, Univ. de Sevilla (Spain)
Ctr. Nacional de Microelectronica (Spain)
Angel Rodriguez-Vazquez, Univ. de Sevilla (Spain)
Ctr. Nacional de Microelectronica (Spain)

Published in SPIE Proceedings Vol. 5119:
Bioengineered and Bioinspired Systems
Angel Rodriguez-Vazquez; Derek Abbott; Ricardo Carmona, Editor(s)

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