Gain/phase compensation for outphasing transmitters targeting LTE applications

This paper presents a new mismatch calibration technique for outphasing transmitters by means of instantaneous measurement characterisation. Results will show that by creating a model of the instantaneous measurements, the gain and phase imbalance between the outphasing paths can be fully compensated using only a single iteration. A multilevel-outphasing transmitter is implemented using 10 W GaN devices at 1.9 GHz. An ACPR performance of -51 dBc and -47 dBc are obtained for 1.4 MHz and 10 MHz LTE signals with a PAPR of 10 dB, respectively, while delivering 2 W average output power without requiring any form of predistortion.