Efficiency boosting of multilevel LINC transmitter

A multilevel output outphasing transmitter has been developed to boost efficiency considerably over regular LINC transmitter. The system consists of four identical class-E power amplifiers (PAs) in hybrid design operating at 3.3 GHz and delivering a peak output power of 40.5 dBm. By controlling the supply voltage of the four PA units a fully symmetrical multilevel outphasing behaviour can be achieved with a power added efficiency (PAE) enhancement over a range of more than 25 dB of output power back-off. By comparing system measurement results with conventional outphasing transmitter a peak PAE enhancement of 33 % points and a maximum DC power saving of 21 Watts were achieved.