A multi-band delay-locked loop with fast-locked and jitter-bounded features

Abstract

In this paper, a multi-band delay-locked loop with fastlocked and jitter-bounded features is presented. A programmable charging voltage circuit to the loop filter is developed to accelerate the locking of DLL. The shortest lock time of the proposed DLL is six clock cycles from the unlocked state. In the presented DLL, two phase-frequency detectors with a tunable delay cell are used to reduce the output clock jitter. A new DLLbased frequency multiplier with less active devices is also proposed to promote the operating frequency range from 200 MHz to 2 GHz. The presented DLL is implemented in a 0.18 μm 1P6M CMOS process. The core area excluding PADs is 0.34× 0.41 mm 2. The power consumption of the presented DLL is 31.5 mW at a 1.8 V of supply voltage. © 2008 IEEE.