Development Of A Doherty Amplifier Utilizing Novel Techniques To Achieve Broad Bandwidth And High Efficiency
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Type of WorkText
DepartmentElectrical and Computer Engineering
ProgramMaster of Science
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The military has a need for power amplifiers (PAs) that are broadband, highly efficient, and have high output power. PAs employing the Doherty configuration are typically known to achieve high efficiency without operating at maximum rated power levels. In this work, multiple Doherty amplifier designs are presented that implement different approaches and are composed of single-ended GaN FETs (T2G6001528-SG) manufactured by Qorvo (Triquint). The first Doherty amplifier was designed for narrowband operation centered at 3 GHz with a maximum PAE = 62% and maximum Pout = 45.63 dBm. Design of another Doherty amplifier with broadband input and output matching networks performed over an extended frequency bandwidth from 2.425 GHz to 3.75 GHz with a maximum PAE = 67.9% and a maximum Pout = 45.8 dBm. In an attempt to abandon conventional design methods, an innovative bandwidth extension technique involving a wideband output combiner for the Doherty amplifier that achieves broadband load modulation has been implemented. This Doherty amplifier design accomplished a dual band operation from 2 GHz to 2.8 GHz and 3.28 GHz to 4 GHz. In the first band, a maximum PAE = 58.7% and maximum Pout = 44.9 dBm was reached. In the second band, a maximum PAE = 47.1% and maximum Pout = 43 dBm was obtained.