AbstractA model combining transmission line modeling (TLM) and exponential switching resistance (ESR) of active devices is introduced in the equivalent circuit to simulate the real performance of the reactively loaded power amplifier. Using the TLM, the distributed circuit parameters can be controlled by the time step size, and the collector efficiency can be more accurately evaluated by introducing the ESR into the equivalent circuit. The TLM together with the ESR element provides a simple algorithm to be implemented, and is favorable for optimization of high‐efficiency performance in the rf range. © 1993 John Wiley & sons, Inc.