Feedback Loops and Large Subcircuits in the Multiprocessor Implementation of a Relaxation Based Circuit Simulator

This paper presents several new methods for the efficient parallel simulation of VLSI circuits that contain feedback loops or "difficult" parts such as arrays, registers and pass-transistor networks. A new parallel algorithm has been developed for the efficient simulation of circuits containing feedback loops. It is based on dataflow scheduling and local relaxation of the loops. For the simulation of large pass-transistor networks a partitioning method is used that is based on signal flow in the elements. Parallel element evaluation and time-segment pipelining are included to increase the performance of the parallel circuit simulator. Simulation tests with actual circuits show a substantial acceleration for the new methods.