PCI Express® Transmitter PLL Testing — A Comparison of Methods

There are several methods of measuring PLL loop response, based on the type of test instrumentation used. As expected, the various methods trade off test accuracy, test speed (throughput), ease of use, ease of setup, and initial cost. In addition, some methods have limitations preventing their universal use on all types of PLLs. While all methods can test compliance to the specification requirements, some offer additional information useful to the clock designer for optimizing a design.