Linear Doherty PA at 5 GHz

At the 2014 International Microwave Symposium (IMS2014) in Tampa, Florida, the power amplifier (PA) design competition celebrated its tenth anniversary. Back in 2004, it was the first student design competition that the IEEE Microwave Theory and Techniques Society (MTT-S) organized and, since then, the only one that has been held regularly every year. We started to participate in this competition in 2012, which also happened to be the year when a significant change in the competition rules was adopted. Starting in 2012, the power-added efficiency (PAE) in the figure of merit (FOM) that is used to evaluate the PAs, FOM = PAE/4?f, was measured at a power level at which the intermodulation distortion (IMD) that the PA produces from a two-tone excitation first exceeds 30 dBc. With that new rule, not only did linearity start to play a major role but also the test signal changed from continuous wave (CW) to a modulated signal with a peak to average ratio of 3 dB.