what is process design kit
A Process Design Kit is a set of libraries, code and specified flows that fit a given set of EDA tools and allows for circuit design with respect to a specific Foundry Process. Depending on the Process in question, these may be either Analog-centric, Digital, or Mixed-Mode. For example, TSMC (Taiwan Semiconductor Manufacturing Corp.) provides a Mixed-Mode reference flow for its 90nm Mixed-Mode process, and provides some of the elements of a PDK through the Cadence PDK development service.