Radio frequency power amplifier circuitry includes an amplifier element, power supply modulation circuitry, and bias modulation circuitry. The amplifier element is configured to amplify an RF input signal using a modulated power supply signal and a modulated bias signal to produce an RF output signal. The power supply modulation circuitry is coupled to the amplifier element and configured to provide the modulated power supply signal. The bias modulation circuitry is coupled to the amplifier element and the power supply modulation circuitry and configured to receive the modulated power supply signal and provide the modulated bias signal. Notably, the modulated bias signal is a function of the modulated power supply signal such that the modulated bias signal is configured to maintain a small signal gain of the amplifier element and the phase of the RF input signal at a constant value as the modulated power supply signal changes.