An Analog Two-Dimensional Discrete Cosine Transform Processor for Focal-Plane Image Compression


IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E80-A   No.2   pp.283-290
Publication Date: 1997/02/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit Techniques for System-on-Chip Integration)
discrete cosine transform,  analog parallel processing,  focal-plane image compression,  smart image sensor,  switched capacitor ciruits,  

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This paper presents an analog 2-dimensional discrete cosine transform (2-D DCT) processor for focal-plane image compression. The on-chip analog 2-D DCT processor can process directly the analog signal of the CMOS image sensor. The analog-to-digital conversion (ADC) is preformed after the 2-D DCT, and this leads to efficient AD conversion of video signals. Most of the 2-D DCT coefficients can be digitized by a relatively low-resolution ADC or a zero detector. The quantization process after the 2-D DCT can be realized by the ADC at the same time. The 88-point analog 2-D DCT processor is designed by switched-capacitor (SC) coefficient multipliers and an SC analog memory based on 0.35µm CMOS technology. The 2-D DCT processor has sufficient precision, high processing speed, low power dissipation, and small silicon area. The resulting smart image sensor chips with data compression and digital transmission functions are useful for the high-speed image acquisition devices and portable digital video camera systems.