A method of calibrating an envelope tracking system, the method comprising: using a scaling module in an envelope tracker, scaling an amplitude of an envelope signal to generate a scaled envelope signal; and generating, at least in part based on the scaled envelope signal, a supply voltage (V CC) for a power amplifier using the envelope tracker, the envelope tracker including a shaping module configured to receive the scaled envelope signal from the scaling module, the shaping module having an envelope shaping table generated at a desired gain compression of the power amplifier; using a calibration module configured to provide calibration data to the scaling module so as to change the scaled envelope signal generated by the scaling module, operating the supply voltage (V CC) of the power amplifier at a first voltage level, the first voltage level associated with no gain compression of the power amplifier; measuring, using a directional coupler and a power detector electrically coupled to the output of the power amplifier, an output power of the power amplifier at the first voltage level; decreasing, by changing the calibration data, a voltage level of the supply voltage (V CC) one or more times and measuring the output power at each decreased voltage level; determining a gain compression at each of the decreased voltage levels; determining a second voltage level of the supply voltage of the power amplifier, selected from the said decreased voltage levels, that is associated with a determined gain compression equal to the desired gain compression; and calibrating the envelope tracker based on the determination to correct for an envelope amplitude misalignment between the supply voltage (V CC) and an input power of the envelope signal, by using the calibration data corresponding to the determined second voltage level to scale the amplitude of the envelope signal. using a scaling module in an envelope tracker, scaling an amplitude of an envelope signal to generate a scaled envelope signal; and generating, at least in part based on the scaled envelope signal, a supply voltage (V CC) for a power amplifier using the envelope tracker, the envelope tracker including a shaping module configured to receive the scaled envelope signal from the scaling module, the shaping module having an envelope shaping table generated at a desired gain compression of the power amplifier; using a calibration module configured to provide calibration data to the scaling module so as to change the scaled envelope signal generated by the scaling module, operating the supply voltage (V CC) of the power amplifier at a first voltage level, the first voltage level associated with no gain compression of the power amplifier; measuring, using a directional coupler and a power detector electrically coupled to the output of the power amplifier, an output power of the power amplifier at the first voltage level; decreasing, by changing the calibration data, a voltage level of the supply voltage (V CC) one or more times and measuring the output power at each decreased voltage level; determining a gain compression at each of the decreased voltage levels; determining a second voltage level of the supply voltage of the power amplifier, selected from the said decreased voltage levels, that is associated with a determined gain compression equal to the desired gain compression; and calibrating the envelope tracker based on the determination to correct for an envelope amplitude misalignment between the supply voltage (V CC) and an input power of the envelope signal, by using the calibration data corresponding to the determined second voltage level to scale the amplitude of the envelope signal.