A power efficient companding LINC architecture

A novel companding LINC architecture is proposed. It consists of compressing the original signal dynamics in the signal decomposition process and then restoring it by expansion at the final amplification stage through proper power control of the switching amplifiers. Comparing to the conventional LINC, the proposed architecture offers significant efficiency improvement especially for signals with a high peak-to-average power ratio. An implementation using a class-F parallel-amplifier with commercial GaN devices is designed and simulated. At 900 MHz the amplifier has a power efficiency of around 78% maintained at both 10 W and 3.2 W output power. For a WCDMA down-link signal, with companding LINC architecture the overall system efficiency is improved to 28% form 11% with the conventional LINC architecture, while still achieving good linearity of -49 dBc adjacent channel power ratio.