A multiplexer based decoder for flash analog-to-digital converters

A decoder for flash analog-to-digital converters with short critical path, regular structure, and small area is presented. The decoder is based on 2:1 multiplexers connected as a tree. Each level of the tree divides the input thermometer scale in two and calculates one of the bits in the binary output. In comparison with the Wallace tree decoder and the folded decoder the length of the critical path is approximately reduced to one third and one half, respectively. The amount of hardware is also reduced, which is likely to translate to a power saving, compared with the Wallace tree decoder and the folded decoder.