Abstract: A Coherent Delay-Locked Loop(CDLL) is proposed based on interpolation and integrate/dump filter for PN code tracking in DS-CDMA systems. The performance of the CDLL is investigated under AWGN and multi-user environments, and closed-form expres-sions for the timing adjustment error probability, steady-state timing squared root error, probability and Mean Time to Lose Lock (MTLL) are derived by employing appropriate Markov chain models. Finally, some numerical results are presented and analysis shows that those results also perform well in single path fading environment. The delay-locked loop is applied to the development of WCDMA BTS and WCDMA MT.