Disclosed is an envelope tracking (ET) system having a transmit (TX) section, a power amplifier (PA), a fast switched-mode power supply (Fast SMPS), and control circuitry. The TX section receives an input signal and provides a modulated signal to the PA. The TX section also generates an ET signal based on a modulation envelope of the modulated signal. The TX section provides an envelope control (EC) signal based on the ET signal to modulate a supply signal provided to the PA by the Fast SMPS. The control circuitry provides a transmit TX gain signal and an ET gain signal to the TX section based on a PA temperature signal, a TX temperature signal, a target power signal, a measured power signal. The control circuitry is configured to maintain the efficiency and linearity of the PA over a wide operating temperature range.