A contrast retina with on-chip calibration for neuromorphic spike-based AER vision systems (2007)
| Venue: | IEEE Trans. on Circuits and Systems-I |
| Citations: | 6 - 2 self |
BibTeX
@ARTICLE{Costas-santos07acontrast,
author = {Jesús Costas-santos and Teresa Serrano-gotarredona and Rafael Serrano-gotarredona and Bernabé Linares-barranco},
title = {A contrast retina with on-chip calibration for neuromorphic spike-based AER vision systems},
journal = {IEEE Trans. on Circuits and Systems-I},
year = {2007},
volume = {54},
pages = {2006}
}
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Abstract
Abstract—We present a 32 32 pixels contrast retina microchip that provides its output as an address event representation (AER) stream. Spatial contrast is computed as the ratio between pixel photocurrent and a local average between neighboring pixels obtained with a diffuser network. This current-based computation produces an important amount of mismatch between neighboring pixels, because the currents can be as low as a few pico-amperes. Consequently, a compact calibration circuitry has been included to trimm each pixel. Measurements show a reduction in mismatch standard deviation from 57 % to 6.6 % (indoor light). The paper describes the design of the pixel with its spatial contrast computation and calibration sections. About one third of pixel area is used for a 5-bit calibration circuit. Area of pixel is SV m ST m, while its current consumption is about 20 nA at 1-kHz event rate. Extensive experimental results are provided for a prototype fabricated in a standard 0.35- m CMOS process. Index Terms—Address-event representation (AER), analog circuits, artifical retina, calibration, contrast computation, currentmode circuits, imagers, low-power circuits and systems, mismatch, neuromorphic circuits, sensory systems, trimming, vision systems, weak inversion circuits. I.
