A fast-lock synchronous multi-phase clock generator based on a time-to-digital converter

An all-digital fast-lock synchronous multi-phase clock generator is presented. By using a time-to-digital converter for fast-lock operation and delay measurement, the proposed multi-phase clock generator generates four-phase clocks and synchronizes the reference clock with the output clock within 45 cycles. Furthermore, the clock generator uses a fine binary scheme and de-skewing circuit for fine delay measurement and compensation. The proposed clock generator was designed in a 0.18 mum CMOS technology. It operates over a wide frequency range from 400 MHz to 1.22 GHz and consumes 34 mW at 1.22 GHz.