AN ANALOG 2-DIMENSIONAL DISCRETE COSINE TRANSFORM PROCESSOR FOR FOCAL-PLANE IMAGE COMPRESSION

This paper presents an analog 2-dimensional discrete cosine transform (2-D DCT) processor for focal-plane image compression. The on-chip ana log 2-D DCT processor can process directly the analog signal of the CM OS image sensor. The analog-to-digital conversion (ADC) is performed a fter the 2-D DCT, and this leads to efficient AD conversion of video s ignals. Most of the 2-D DCT coefficients can be digitized by a relativ ely low-resolution ADC or a zero detector. The quantization process af ter the 2-D DCT can be realized by the ADC at the same time. The 8 x 8 -point analog 2-D DCT processor is designed by switched-capacitor (SC) coefficient multipliers and an SC analog memory based on 0.35 mu m CM OS technology. The 2-D DCT processor has sufficient precision, high pr ocessing speed, low power dissipation, and small silicon area. The res ulting smart image sensor chips with data compression and digital tran smission functions are useful for the high-speed image acquisition dev ices and portable digital video camera systems.