Salphasic Distribution of Clock Signals

The design of a synchronous system having a global clock must account for the phase shifts experienced by the clock signal (clock skew) in its distribution network. As clock speeds and system diameters increase, this requirement becomes increasingly constraining on system designs. Two currently used approaches to this problem are to minimize skew by equalizing electrical path delays, and to re-cast system designs into an asynchronous (clockless) form. This paper describes a method that exploits fundamental wave propagation properties to minimize clock skews due to unequal path lengths for distribution system diameters typically up to several meters. The basic principles are developed for a loaded transmission line, then applied to an arbitrarily branching tree of such lines to implement a clock distribution network. Extension of this method to twoand three-dimensional distribution media is discussed.