Grid selection strategies for time-mapped harmonic balance simulation of circuits with rapid transitions

The time-mapped harmonic balance (TMHB) method overcomes the inefficiency of standard harmonic balance for computing steady-state solutions of circuits with rapid transitions. TMHB features a nonuniform grid to resolve the sharp features in the signals. The success of TMHB is critically dependent on the selection of this nonuniform grid. After a brief discussion of TMHB, two grid selection strategies, direct and iterative, are examined. Results on several circuit examples indicate that the iterative strategy is the best. Compared to standard harmonic balance, up to five orders of magnitude accuracy improvements, and up to a factor of six simulation time speedups and memory savings are achieved.