SALPHASIC DISTRIBUTION OF CLOCK SIGNALS FOR SYNCHRONOUS SYSTEMS

The design of a synchronous system having a global clock must account for propagation-delay-induced phase shifts experienced by the clock si gnal (clock skew) in its distribution network. As clock speeds and sys tem diameters increase, this requirement becomes increasingly constrai ning on system designs. This paper describes a method that exploits pr operties of standing waves to reduce substantially clock skews due to unequal path lengths, for distribution network diameters up to several meters. The basic principles are developed for a loaded transmission line, and then applied to an arbitrary branching tree of such lines to implement a clock distribution network. The extension of this method to two- and three-dimensional distribution media is also presented, su ggesting the feasibility of implementing printed circuit board clock p lanes exhibiting negligible phase shift over their extents.