MULTI-BIT EXCLUSIVE OR

The present invention relates to multi-bit exclusive-or (XOR) gates (60), including those where N parallel input bits (36, 38) are XORed with one data input bit (52). A modular approach is made using only one basic cell (30) for various implementations with different propagation delays. An N-bit XOR comprises basic cells (30) of adjacent first and second XOR gates (32, 34). Each first XOR gate (32) processes as input two of said N primary input bits (36, 38) and each second XOR gate (34) processes as input bits output bits of first or second XOR gates (32, 34) or the input data bit (52). This structure makes it possible to create an array of identical basic cells which is very suitable for VLSI implementation. There are few lines of connections between the different cells in the cell array which leads to substantial reduction in propagation delay without adding substantial wiring or layout complexity.