Analog Circuit Design Volume 2

Chapter 31

Circuit techniques for clock sources

Jim Williams

Almost all digital or communication systems require some form of clock source. Generating accurate and stable clock signals is often a difficult design problem.

Quartz crystals are the basis for most clock sources. The combination of high Q, stability vs time and temperature, and wide available frequency range make crystals a price-performance bargain. Unfortunately, relatively little information has appeared on circuitry for crystals and engineers often view crystal circuitry as a black art, best left to a few skilled practitioners (see box, “About Quartz Crystals”).

In fact, the highest performance crystal clock circuitry does demand a variety of complex considerations and subtle ...