Mean time to lose lock for a coherent extended tracking range delay-locked loop

The delay-locked loop (DLL) is an appropriate device to guarantee fine synchronization for direct-sequence spread spectrum systems. The mean time to lose lock (MTLL) is a good performance criteria for the DLL operating at low signal to noise ratios. In the paper, the influence of the extended tracking range on the MTLL for a coherent DLL is investigated. A second order loop with passive loop filter is considered. The MTLL is approximated by an explicit expression for the leading order term based on results by Kramers (1940). The results compare the MTLL for different coherent DLL structures