1.25/2.5-Gb/s Dual Bit-Rate Burst-Mode Clock Recovery Circuits in 0.18-$\mu\hbox{m}$ CMOS Technology

A burst-mode clock recovery circuit with a novel dual bit-rate structure is presented. It utilizes two gated oscillators to align the clock with data edges and can operate in half-rate clocking mode, doubling data throughput, as well as in full-rate clocking mode. The gated oscillator reset-phase control scheme causes the starting phase of gated oscillators to alternate repeatedly between 0deg and 180deg according to the current clock phase. A prototype chip was designed with the 0.18-mum CMOS technology, and a 1.25/2.5-Gb/s dual-mode operation was verified by measurement