A Harmonic-Free and Fast-Locking Delay-Locked Loop Adopting a Resettable Delay Line

Abstract

An all digital delay-locked loop (ADDLL) with "reset in every step" (RES) delay line is developed in order to reduce the locking time. Due to the novel resettable mechanism of delay line, the DLL has the property of fast-locking and harmonic-free. The locking time can be reduced to N+1, where N is the bits' number of the control code for a delay line. According to the simulation result in SMIC 180nm CMOS technology, the proposed delay-locked loop (DLL) can cover the operating range from 50 to 250MHz.