Chapter 12. Phase Lock Loops

Summary

Phase lock loops (PLL) are not a recent invention. Their use became widespread with the availability of high-quality integrated circuit operational amplifiers (op-amps) in the 1960s. This versatile circuit has found applications across the frequency spectrum in consumer, commercial, deep space, and military projects. Tracking Voyager through the solar system and tuning a car radio are made to order uses for a PLL. To understand a PLL, a good working knowledge of RF techniques, oscillator design, closed loop control theory, analog circuit design, and digital circuit design is required. A comprehension of each of the components and its place in the system is essential. Fortunately not all of this knowledge is required at once. The references listed at the end of this chapter can each provide an in-depth insight into areas beyond the present scope. This discussion begins with the basic concepts and rapidly expands these ideas into practical considerations.