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This paper describes the analysis of an optimized envelope shaping function for the envelope tracking power amplifier (ET PA) and its implementation. The proposed shaping function, which is sweet spot tracking with crest factor reduction, improves the efficiency and output power of the power amplifier (PA), as well as its linearity. For an accurate simulation of the supply modulator, an equivalent model of the PA under the envelope shaping is suggested. To achieve high efficiency and wide bandwidth, the CMOS supply modulator has a hybrid structure of a switching amplifier and a linear amplifier. The fabricated ET PA delivers higher efficiency and better linearity than standalone PA for the wideband code division multiple access and long-term evolution signals.