Patent ID: 8989682
Filing Date: 2015-03-24
Classification: H03F,H03G,H04B,H04W

Abstract:
1. A method of calibrating an envelope tracking system, the method comprising: generating a supply voltage for a power amplifier using an envelope tracker having an envelope shaping table including shaping data generated at a desired gain compression of the power amplifier relating a plurality of scaled envelope signal amplitudes to a plurality of supply voltage levels; operating the supply voltage of the power amplifier at a first voltage level, the first voltage level associated with substantially no gain compression of the power amplifier; measuring an output power of the power amplifier at the first voltage level; decreasing a voltage level of the supply voltage 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 corresponding to one of the decreased voltage levels that is associated with the determined gain compression equal to about that of the desired gain compression; retrieving the scaled envelope signal amplitude associated with the second voltage level from the envelope shaping table; and calibrating the envelope tracker based on the retrieved scaled envelope signal amplitude to correct for an envelope amplitude misalignment of the envelope tracker.