Reliable design of multichip nonblocking crossbars

A major problem in the design of VLSI crossbar networks is the simultaneous-switching noise (also known as Delta-I noise), caused by the simultaneous activation of a large number of line-drivers at the output leads of the VLSI package. In a nonblocking configuration, one can reduce the maximum number of active line-drivers in a chip by using extra columns of chips. Tight upper and lower bounds are derived for the number of additional columns required for a one-sided nonblocking crossbar network when a Delta-I constraint is imposed. By using algorithms that allocate paths intelligently, a substantial reduction in the Delta-I constraint is imposed. A substantial reduction in the Delta-I noise can be achieved with a modest hardware overhead, if a small blocking probability is acceptable. The first-fit and the best-fit case bus-allocation policies are introduced