Clock signal distribution system

Abstract

A system for distributing synchronous clock signals includes a set of spatially distributed deskewing stages. Each stage includes matching adjustable first and second delay circuits and a phase lock loop controller. Matching pairs of transmission lines interconnect successive stages of the set. One transmission line of each pair connects the output of the first delay circuit of each stage to the input of the first delay circuit of a next stage of the set. The other transmission line of the pair connects the input of the second delay circuit of the stage to the input of the first delay circuit of the next stage. When the first delay circuit of the first stage of the set receives an input reference clock signal, that reference clock signal propagates through all the first delay circuits of each stage in succession. Whenever the input reference clock signal reaches a stage, it also travels back to the second delay circuit of the preceding stage. The phase lock loop controller in each stage adjusts the similar delay provided by its first and second delay circuits to phase lock the output second delay circuit to the input of the first delay circuit. Each stage also includes a frequency multiplier for doubling the frequency of its first input signal thereby to produce one of the spatially distributed local clock signals.