A device for controlling operation of a power amplifier includes a detector, a reference signal generator and a controller. The detector is configured to detect a voltage level of an output signal of the power amplifier with respect to a predetermined boost threshold and to generate a corresponding detection signal and a reference signal. The controller is configured to provide a supply voltage to an output transistor of the power amplifier based on a comparison of the detection signal and the reference signal, the supply voltage being a no boost voltage, which is substantially the same as a supply voltage, when the comparison indicates that the voltage level is within the predetermined boost threshold, and the supply voltage being one of multiple boost voltages when the detection signal indicates that the voltage level is beyond the predetermined boost threshold. The controller generates the boost voltages by boosting the supply voltage.