A power amplifying apparatus is provided. A reference signal generator provides a reference signal having an enabling state and a disabling state. A digital power amplifier generates a current based on the reference signal and an input signal. An output signal of the digital power amplifier is related to the current. When the reference signal is in the enabling state, the current is related to the input signal. When the reference signal is in the disabling state, the current is irrelevant to the input signal. During the enabling state of the reference signal, a data generator provides an output alternating between an in-phase signal and a quadrature-phase signal as the input signal to the digital power amplifier. When the reference signal is in the disabling state, the data generator provides a fixed signal as the input signal to the digital power amplifier.