Design of Delay-Locked Loop (DLL) with Low Jitter and High Lose Lock Time in UWB-IR System

Ultra-wide band impulse radio (UWB-IR) transmits data using sub-nanosecond baseband pulses with very low duty cycle. It is a promising candidate for short-range communications. However, due to the short duration of the impulse signal, very precise synchronization control is vital for the whole system. In this paper, an improved delay-locked loop (DLL) is introduced to the UWB-IR system with time hopping/spread spectrum (TH/SS). Instead of using only two central correlator branches in the DLL, more correlator branches with different delay parameters and different weight parameters are added to the conventional DLL. Lower tracking jitter and higher mean time to lose lock (MTLL) than the conventional systems can be achieved from proposed ones. Performance of several different combinations of correlator parameters are evaluated in this paper and some of them perform superior to that of the conventional DLLs