Design and integration of hybrid and monolithic microwave power amplifiers for wideband applications using gallium nitride technology
Barisich, George Christopher
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The objective of this research is to compare and advance the predominant methods of realizing broadband microwave power amplifiers (PAs) up to 40 GHz with high efficiency using gallium nitride (GaN) technology. The studied architectures are based on the reactive/resistive matching approach and the traveling wave technique in both hybrid and monolithic microwave integrated circuits (MMICs). Important details of design development and integration are discussed, featuring discrete component descriptions, substrate material selections, additional matching techniques, and comparisons of both wirebonds and flip-chip bonds that are used for PA interconnections. With a focus on bandwidth enhancements and efficiency improvements, the presented hybrid PA designs achieve state of the art performance with commercially-available GaN power transistors. This part of the work demonstrates the highest power added efficiency (27–48%) and widest bandwidth (1.0-11.5 GHz) for a multi watt hybrid PA implementation. To complement these novel hybrid PA designs and integration developments, broadband MMIC PAs were designed at higher frequencies. The results of device characterization and wideband modeling are presented for a new 0.15 µm GaN process in support of a 3 stage broadband MMIC PA design with reactive/resistive matching. Lastly, an ultra-wideband non-uniform distributed PA design is fabricated on a pre-release version of a new 0.14 µm GaN process. For the first time, a GaN MMIC PA with output power greater than 1 W and nearly 10% power added efficiency was successfully achieved from 2 to 40 GHz, surpassing previously reported results.