Design and implementation of a 9W, 0.3 – 3.7 GHz linear power amplifier using GaN HEMT

This paper presents a design for a highly-linear power amplifier - based on GaN HEMT- with an output power excess of 9W, and an ultra-broad bandwidth extending from 0.3 to 3.7 GHz (170%). Different design techniques are adopted to achieve a flat power gain of 9.5 ± 1 dB over the entire operating bandwidth. Sixth and fifth order low pass matching circuits are designed for input and output matching, respectively, providing optimal fundamental and harmonic impedances within more than 3 octaves of operation. The designed power amplifier exhibits a small signal gain more than 9.5-dB, an input/output return loss better than 10 dB within the operation bandwidth. Second and third-harmonic inter-modulation distortions are far below -36dBc and -45dBc @ 3GHz, respectively, at an input power of 30-dBm over the entire frequency band, while achieving a power added efficiency (PAE) better than 25%. At a frequency spacing of 160 KHz, a maximum value of the output OIP2 and OIP3 are found to be greater than 50-dBm, and 60-dBm, respectively.