Fast Electromagnetics-Based Co-Simulation of Linear Network and Nonlinear Circuits for the Analysis of High-Speed Integrated Circuits

Abstract

A fast electromagnetic simulator is developed to co-simulate the linear network and nonlinear circuits in an integrated circuit system. In this simulator, the physical layout of a large-scale linear network is rigorously reduced to a single surface or a few surfaces where the nonlinear circuits are located. The reduction is done analytically, and, hence, the computational overhead is minimal. The reduced system is then split into a linear system and a nonlinear system so that both systems can be solved efficiently. The linear system of equations is solved rapidly by the time-domain layered finite-element reduction-recovery method. The nonlinear system of equations is solved by developing an efficient method. This method renders the contribution from the linear network to the nonlinear system a diagonal matrix in the Jacobian matrix, hence significantly speeding up the nonlinear solution. After the reduced system is solved, the unknowns elsewhere in the computational domain are recovered efficiently by the time-domain layered finite-element reduction-recovery method. The proposed simulator has been applied to co-simulate on-chip interconnects and CMOS transistors. Numerical results have demonstrated its accuracy and efficiency. The proposed simulator is capable of capturing the global electrical interaction between integrated circuit interconnects, package, RF/analog components, substrates, and nonlinear drivers/receivers across the full electromagnetic spectrum. In addition, it bypasses the extraction of the linear network, preserves the passivity and stability of the linear network, and captures the interaction between the linear network and nonlinear devices.