A Static Pattern-Independent Technique For Power Grid Voltage Integrity Verification

Design verification must include the power grid. Checking that the voltage on the power grid does not drop by more than some critical threshold is a very difficult problem, for at least two read sons: i) the obviously large size of the power grids for modern high-performance chips, and ii) the difficulty of setting up the right simulation conditions for the power grid that provide some measure of a realistic worst case voltage drop. The huge number of possible circuit operational modes or workloads makes it impossible to do exhaustive analysis. We propose a static technique for power grid verification, where static is in the sense of static timing analysis, meaning that it does not depend on, nor require, user-specified stimulus to drive a simulation. The verification is posed as an optimization problem under user-supplied current constraints. We propose that current constraints are the right kind of abstraction to use in order to develop a practical methodology for power grid verification. We present our verification approach, and report on the results of applying it to a number of test-case power grids.