Rapid and Accurate Latch Characterization via Direct Newton Solution of Setup/Hold Times

Abstract

Characterizing setup/hold times of latches and registers, a crucial component for achieving timing closure of large digital designs, typically occupies months of computation in industries such as Intel and IBM. We present a novel approach to speed up latch characterization by formulating the setup/hold time problem as a scalar nonlinear equation h(tau) = 0 derived using state-transition functions, and then solving this equation by Newton-Raphson (NR). The local quadratic convergence of NR results in rapid improvements in accuracy at every iteration, thereby significantly reducing the computation needed for accurate determination of setup/hold times. We validate the fast convergence and computational advantage of the new method on transmission gate and C2MOS latch/register structures, obtaining speedups of 4-10times over the current standard of binary search