Reduction of simultaneous-switching noise in large crossbar networks

Delta-I noise (simultaneous switching noise) poses a severe limitation on the size of the individual crosspoint chips that can be used to synthesize a large crossbar network. An architectural solution for reduction of the Delta-I noise in a crossbar network by using a one-sided crosspoint switching circuits is presented. Because of the existence of multiple switching paths between any pair of terminals to be connected, these circuits provide the potential for minimizing the Delta-I noise by placing the active line drivers uniformly among the switching chips. It is shown that when the sequence of connections and disconnections is arbitrary, and with a minimal nonblocking configuration of one-sided switching chips, no algorithm exists for allocation of paths in the network that can prevent the active line drivers from getting concentrated in a few chips. However, it is possible to reduce the maximum number of active line drivers in a chip by using extra columns of chips. Tight upper bounds are achieved for the number of additional columns required for a one-sided nonblocking crossbar network when a Delta-I constraint is imposed