A repository, a loader, a model generator, a constraint generator, and a number of timing analysis tools, are provided for managing timing requirement specifications and measurements, and generating timing models and constraints of a VLSI circuit. The repository stores the timing specifications and measurements for each pin instances and each flow through arc instances. Timing specifications and measurements are identified by their classes including at least one current specification class and at least one measurement class for one timing analysis tool. Additionally, the repository stores a number of characteristics for each pin instance, the pin compositions of each net, and the hierarchical relationship of the functional block instances. The loader loads the various information into the repository. The timing model generator generates the timing models for the various functional blocks, using the stored information in the repository. The timing constraint generator in cooperation with the timing model generator and at least one timing analysis tool generates the timing constraints for the various functional block instances, using the stored information in the repository, the generated timing models of the functional blocks, and a number of timing analysis scripts.