Characterization of subthreshold MOS mismatch in transistors for VLSI systems
Journal of VLSI Signal Processing Systems - Joint special issue on Analog VLSI computation; also see Analog Integrated Circuits Signal Process., Vol. 6, No. 1
An Analog Integrated Circuit for Continuous-Time Gain andOffset Calibration of Sensor Arrays
Analog Integrated Circuits and Signal Processing
IEEE Micro
Adaptation of Current Signals with Floating-Gate Circuits
MICRONEURO '99 Proceedings of the 7th International Conference on Microelectronics for Neural, Fuzzy and Bio-Inspired Systems
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Stochastic adaptive algorithms are investigated for on-line correction of spatial non-uniformity in random-access addressable imaging systems. The adaptive architecture is implemented in analog VLSI, and is integrated with the photo sensors on the focal plane. Random sequences of address locations selected with controlled statistics are used to adaptively equalize the intensity distribution at variable spatial scales. Through a logarithmic transformation of system variables, adaptive gain correction is achieved through offset correction in the logarithmic domain. This idea is particularly attractive for compact implementation using translinear floating-gate MOS circuits. Furthermore, the same architecture and random addressing provide for oversampled binary encoding of the image resulting in an equalized intensity histogram. The techniques apply to a variety of solid-state imagers, such as artificial retinas, active pixel sensors and IR sensor arrays. Experimental results confirm gain correction and histogram equalization in a 64×64 pixel adaptive array integrated on a 2.2 mm×2.25 mm chip in 1.5 µm CMOS technology.