US Patent 9167514 Unequal amplifier gain compression via shaping table

A communication device, such as a smart phone, includes an envelope tracking power supply that provides a voltage supply signal for a power amplifier. The envelope tracking signal input to the envelope tracking power supply arises from application of a shaping table on a desired transmit signal. The shaping table implements non-uniform gain compression across a range of output powers, and in particular may aggressively compress the power amplifier for low output powers, and less aggressively compress the power amplifier at high output powers. The non-uniform gain implemented via the shaping table may provide significant power savings, while still allowing the transmitter to meet spectral mask requirements.