This PTM covers the following topics: What is a clock tree, clock tree components, when to use a clock versus a crystal, what is a free-running clock versus a synchronous clock, clock jitter, and how to estimate clock tree jitter. Estimating clock tree jitter is a critical part in hardware design because jitter affects the performance of a design. Upon understanding these concepts, a few application examples will be applied to build a clock tree with optimized performance.