The Design of Linearized Power Amplifier for Wireless Communications

Abstract

The interest in higher data rate systems is rising very quickly in the area of wireless communications. High data rates mean high Peak to Average Ratio, PAR. This imposes big challenge on the linearity requirement of Power Amplifiers, PAs. The simplest technique that has been used is backing off the PA. However, this leads to very inefficient performance. A lot of more complex techniques were suggested in the literatures to trick the tradeoff between linearity and efficiency. So we discuss the advantages and disadvantages of those techniques. In addition we suggest a new technique called Power Amplifier Linearization using a Mirror Predistorter. This technique is based on the use of a mirror PA that generates a copy of the main PA nonlinearity, and then feeds it in the proper phase and magnitude into the input in order to cancel the intermodulation terms at the output. Simulation and on the bench lab results validate the suggested technique. Also a hybrid PA module was designed and tested based on the suggested technique, and showed an improvement of 23 dB in the Third Order Intermodulation to Carrier ratio, IMD3 of the PA at 7.5 dB back off.