On challenges for implementing pixelwise DA converter in 3D

Vision chips are natural candidates for being among the first areas that are able to utilize the emerging 3D integration possibilities. In some 2D vision chip architectures there are pixel level AD and/or DA converters that are used for various purposes. This article covers the challenges and needs when targeting a megapixel architecture within a 1cm² chip area. The Through-Silicon-Vias (TSVs) on one hand allow the 3D integration, but on the other hand pose strict challenges for the design. The TSVs occupy certain area and in an area restricted design, the number of TSVs should be minimized. Also the associated Keep-Out-Zone (KOZ) for each TSV should be taken into account.