High-efficiency GaN class-E power amplifier with compact harmonic-suppression network

This paper presents a high efficiency class-E power amplifier (PA) suitable for wireless transmitters operating at 2 GHz. Compact impedance transformation network is designed, using micro-strip transmission lines, so that it simultaneously achieves fundamental load transformation and harmonic impedance control using only two open-circuit stubs (2fo, 3fo). The dimensions of the network´s elements were determined in order to concurrently attain a high harmonic suppression, minimum loss and high power added efficiency. The measurement results of the PA prototype, which is designed using a 10 W gallium nitride (GaN) HEMT transistor, showed state-of-the-art drain and power added efficiency (PAE). The achieved PAE, power gain and output power, when the drain is biased at 50 V, were equal to 74%, 12.6 dB and 11.4 W respectively. In addition, a second and third harmonic suppression in excess of -40 dBc and -75 dBc, respectively, is achieved without extra circuit tuning or additional filtering.