Jitter of Delay-Locked Loops Due to PFD

In this paper, delay-locked loop's (DLLs) jitter due to uncertainties in the phase frequency detector (PFD) is calculated. First, time-domain equations of the DLL are introduced. These equations are the key to obtaining a closed-form equation related to the jitter of DLL in presence of a noisy PFD. Jitter equations at the output of all stages are calculated theoretically. A DLL is designed in 0.18-μm CMOS technology to validate the obtained equations.