Linearity/efficiency trade-off according to back off for HPA GaN using mm-Wave modulated signals

Abstract

The evolution of wireless communication systems leads to an increasing use of mm-wave. This makes it possible to achieve very high data rates using OFDM signals with a large instantaneous bandwidth. These signals, however, have high PAPR values, which deteriorates the efficiency of power amplifiers due to large back-off values. At the same time, the development of GaN technologies allows high power levels to be achieved at base stations. This paper studies two back-off points using single carrier QPSK and 256QAM signals with a large instantaneous bandwidth. Taking advantage of specific features of the nonlinear behavior of GaN, the first back off is fixed as a function of the maximum power added efficiency (PAE). The second is set as a function of the 3dB compression point. The complexity and consumption of the linearization technique are taken into account when evaluating the performance of these back-offs. Experimental results show a 10-percentage-point increase of PAE without significant deterioration in the linearity and complexity/consumption of future DPD (Digital Predistortion) with the first back-off.