A 250-MHz-2-GHz wide-range delay-locked loop

Abstract

This paper describes a wide-range delay-locked loop (DLL) for a synchronous clocking which supports dynamic frequency scaling and dynamic voltage scaling. The DLL has wide operating range by using multiple phases from its delay line. A phase detector (PD) which combines linear and binary characteristics achieves low jitter and fast locking speed. A pulse reshaper makes output pulses of the phase detector have variable pulsewidth and variable voltage level to mitigate the static phase error due to the inherent mismatch of the charge pump. The DLL operates in the range from 250 MHz to 2 GHz. At 1 GHz operating frequency, RMS jitter and peak-to-peak jitter are 1.57 ps and 10.7 ps, respectively.