Design of a 10W, highly linear, ultra wideband power amplifier based on GaN HEMT

This paper presents a design for a highly-linear power amplifier - based on GaN HEMT- with an output power of more than 10 W, and an ultra-broadband bandwidth extending from 0.8 to 4.2 GHz (136%). Different design techniques are adopted to achieve a flat power gain of 10 ± 1.5 dB over the entire operating bandwidth. Eighth order low pass filter matching circuits are designed for input and output matching networks, providing optimal fundamental and harmonic impedances within more than 2 octaves of operation. The designed power amplifier exhibits a small signal gain more than 10 dB, an input/output return loss better than 10 dB within the operation bandwidth. Second and third-harmonic intermodulation distortion are far below -36 dBc and -45 dBc, respectively, at an input power of 30 dBm over the entire frequency band, while achieving a power added efficiency (PAE) better than 25%. Using a two-tone testbench with a frequency spacing of 8 MHz, a maximum value of the output OIP2 and OIP3 are found to be greater than 50 dBm, and 60 dBm, respectively.