An envelope tracking (ET) amplifier circuit is provided. The voltage mDPD circuit is provided in an ET amplifier circuit and configured to determine a voltage deviation relative to an ET modulated target voltage signal, execute an mDPD polynomial in one or more iterations to extract an mDPD coefficient(s), and adjust a time-variant target voltage envelope of the ET modulated target voltage signal based on the mDPD coefficient(s) extracted in each of the mDPD iterations to reduce the voltage deviation to a predefined threshold. By reducing the voltage deviation in the ET modulated voltage, it is possible improve linearity (e.g., gain linearity) of the ET amplifier circuit, which can lead to reduced power consumption and improved radio frequency (RF) performance.