A tutorial of phase-locked loops from analogue implementations to digital and optical designs. This text establishes a foundation of continuous-time analysis techniques and maintains a consistent notation as discrete-time and non-uniform sampling are presented. It examines charge pumps and the complementary sequential phase detector. Frequency synthesizers and digital divider analysis/techniques are also included in this edition. Starting with a historical overview, presenting analogue, digital, and optical PLLs, discussing phase noise analysis, and including circuits/algorithms for data synchronization, this volume illustrates the techniques being used in this field. The subjects covered include: development of phase-locked loops from analogue to digital and optical, with notation throughout; expanded coverage of the loop filters used to design second- and third-order PLLs; design examples on delay-locked loops used to synchronize circuits on CPUs and ASICS; new material on digital dividers that dominate a frequency synthesizer's noise floor; techniques to analytically estimate the phase noise of a divider; presentation of optical phase-locked loops with primers on the optical components and fundamentals of optical mixing; a section on automatic frequency control to provide frequency-locking of the lasers instead of phase-locking; and a presentation of charge pumps, counters, and delay-locked loops. This volume includes the topics that should be of interest to wireless, optics, and the traditional phase-locked loop specialist to design circuits and software algorithms.