A Miniaturized WiMAX Band 4-W Class-F GaN HEMT Power Amplifier Module

In this paper, the design and fabrication of a miniaturized 4-W power amplifier for the WiMAX frequency band (2.3-2.7 GHz) is presented. The selected active device is a commercially available GaN HEMT chip from TriQuint Semiconducotr Inc., Hillsboro, OR. The optimum input and output impedances of the GaN HEMT at fundamental frequency are extracted using a custom designed tuning jig. A novel output matching network for class-F operation is proposed and designed using the measured impedances. For integration in a small package, the input and output matching networks are implemented using spiral inductors and interdigital capacitors, and their dimensions were determined using electromagnetic simulation. The fabricated power amplifier is 4.4 × 4.4 mm² and has an efficiency above 50% and harmonic suppression above 40 dBc for second and third harmonics at an output power of 36 dBm.