ABSTRACTIn this work, we analyze the conduction and switching losses of a supply modulator for envelope‐tracking techniques. In particular, the conduction and switching losses in the class‐D chain of the supply modulator are calculated to enhance the efficiency of the supply modulator. From the calculated results, the number of stages and fan‐out in the multiple stages of the class‐D chain are optimized. To verify the feasibility of the analyzed results, we designed a supply modulator using a 180‐nm RF CMOS process. From the measured results, we successfully prove the feasibility of the analyzed results. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1579–1983, 2015