Performance Characteristics of S-Band GaN HEMT-based RF Power Amplifier Implemented on DC Bias Limitation

This paper discusses the development of a radio frequency (RF) power amplifier based on a Gallium Nitride High Electron Mobility Transistor (GaN HEMT) technology and its performance characteristics. The proposed power amplifier which is implemented using a single class-AB amplifier on limited DC bias voltage aims to deliver high output power for S-band applications. To determine the performance characteristics of proposed power amplifier, a parametric study on microstrip transmission line is presented. Width and length of the micostrip lines are investigated and optimized in terms of reflection coefficient (S <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf> ) and transmission coefficient (S <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</inf> ). The implementation of proposed power amplifier uses a 0.813 mm thick Rogers/Duroid RO4003C dielectric substrate with the size of 92 mm × 60 mm. The measurement results provide a maximum gain of 13 dB at the frequency of 2.6 GHz with the 3 dB working bandwidth up to 1.2 GHz. The proposed RF power amplifier demonstrates the feasibility of utilizing GaN HEMT technology in class-AB amplifier and provides a fundamental configuration for further developments.