Development of Efficient High Power Amplifier With More Than an Octave Bandwidth

This paper presents a design of a GaN HEMT-based power amplifier (PA), with enhanced efficiency and linearity over the operation band from 0.5 to 1.5 GHz. The design is based on wideband load-pull and source-pull analysis. A novel procedure is developed to optimize the impedance values and synthesize the matching networks. The amplifier achieves drain efficiency of 40%-68% and power added efficiency (PAE) of 35.7%-63.8%, over the entire frequency band measured for an input power of 24 dBm. To ensure flat gain response, a high pass filter is deployed at the input of the PA, thus achieving a gain of 13.8 ±1 dB for the entire band. Wideband matching circuits are realized on Taconic RF35 with dielectric constant of 3.5 and thickness of 0.76 mm. The PA is found to maintain output power of 36.8-38.3 dBm across the frequency band. Carrier to intermodulation distortion ratio for two-tone input signal with 24-dBm power per-tone and a spacing of 5 MHz is found to be better than 30 dB. In addition, the PA is tested for frequency spacing values of 20 and 25 MHz and good linearity levels are attained. The developed PA thus provides attractive features related to efficiency, linearity, and extended bandwidth, which make this amplifier appropriate for implementations in various wireless communications systems.