Compact Load-Coupling Network for Microwave Current Mode Class-D Power Amplifiers

This paper presents the design and implementation of a highly efficient current-mode class D (CMCD) power amplifier (PA) using a 2W GaN HEMT device. A switched-based model was developed in-house for the commercially available GaN power device and used extensively for the analysis and the design of the CMCD PA. The compact load coupling network, comprising a load transformation network, a higher harmonic impedance termination tank and a balun, used for the 1 GHz power amplifier measures only 37 mm times 76 mm while providing suitable means for tuning the performance of the amplifier. The fabricated CMCD PA achieves a drain efficiency of 65% for an output power of around 36 dBm with more than 7.4 dB of power gain at 1 GHz.