Wiring-optimal method to route high performance clock nets satisfying electrical and reliability constraints

Abstract

High performance clock distributions and similar wiring networks require improvements in reliability and performance. This is especially true when hierarchical wiring with different metal thicknesses is employed and when a smaller number of large, higher-power buffers are used to reduce timing variability. Routing of critical nets improves robustness, reliability, and resistance while minimizing track and power usage. The method further optimizes the use of multiple physical pins on buffers to achieve desired electrical criteria. This involves optimal selection of additional routing beyond what is needed to satisfy simple connectivity. The routing involves an iterative process to select and evaluate additional possible routes on multiple layers. Each iteration involves extraction and simulation or estimation, and additional routes are added until the desired electrical criteria are met.