A switched capacitor modulator (SCM) includes a RF power amplifier. The RF power amplifier receives a rectified voltage and a RF drive signal and modulates an input signal in accordance with the rectified voltage to generate a RF output signal to an output terminal. A reactance in parallel with the output terminal is configured to vary in response to a control signal to vary an equivalent reactance in parallel with the output terminal. A controller generates the control signal and a commanded phase. The commanded phase controls the RF drive signal. The reactance is at least one of a capacitance or an inductance, and the capacitance or the inductance varies in accordance with the control signal.