Accelerating Clock Mesh Simulation Using Matrix-Level Macromodels and Dynamic Time Step Rounding

Xiaoji Ye1,  Min Zhao2,  Rajendran Panda3,  Peng Li1,  Jiang Hu1
1Texas A&M University, 2Magma Design Automation, Inc., 3Freescale Semiconductor, Inc.


In this paper, we present a new simulation methodology which decomposes a clock mesh into linear and nonlinear parts. By exploiting the special matrix property of the linear subsystem resulted from modified nodal analysis (MNA) formulation, the linear subsystem is represented as a matrix-level macromodel, which greatly simplifies the overall simulation task. These macromodels can be efficiently computed using Cholesky factorization and significantly speedup the nonlinear Newton-Raphson iterations used in the transient simulation for the complete clock mesh. Furthermore, a dynamic time step rounding technique is proposed to limit the number of passive macromodels needed in the entire transient simulation and hence further improves the efficiency of the proposed approach.