Two Designs of a Fault-Tolerant Clocking System

Abstract

Two designs of a fault-tolerant clocking system are described: a time-discrete design based on autonomous oscillators and a time-continuous design based on voltage-controlled oscillators. In both designs the system consists of a number of identical modules producing as many mutually synchronous binary clock signals. The system is fault-tolerant in that if at most f modules fail, the remaining modules continue to produce synchronous clock signals. The minimum configuration, i.e., the minimum number of modules that guarantees a fault-tolerant operation, is either 3f + 1 or 2f + 1, depending on both the design chosen (time-discrete or time-continuous) and the assumed fault model.