Gallium Nitride-Based HEMTs for Microwave Power and Noise: Physics and Application
Schwindt, Randal Scott
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https://hdl.handle.net/2142/80884
Description
Title
Gallium Nitride-Based HEMTs for Microwave Power and Noise: Physics and Application
Author(s)
Schwindt, Randal Scott
Issue Date
2004
Doctoral Committee Chair(s)
Adesida, Ilesanmi
Department of Study
Electrical Engineering
Discipline
Electrical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Electronics and Electrical
Language
eng
Abstract
AlGaN/GaN high electron mobility transistors (HEMTs) have shown promising high speed performance, both high microwave power and low microwave noise. In this dissertation, the millimeter-wave and microwave power performance and small signal and low noise microwave characteristics are investigated. The CW power performance at 20 GHz and 30 GHz of 0.25 mum x 100 mum AlGaN/GaN HEMTs grown by metal-organic chemical vapor deposition (MOCVD) on semi-insulating SiC substrates is reported. Saturated output power at 20 GHz was 6.4 W/mm with 16% power added efficiency (PAE), and output power at 1-dB compression at 30 GHz was 4.0 W/mm with 20% PAE. This is the highest power reported for 0.25-mum gate-length devices at 20 GHz, and the 30 GHz results are among the highest power millimeter-wave power data published to date on GaN-based devices. This work also investigates the dependence of power performance on bias and temperature. The small signal performance on bias and temperature of GaN-based HEMTs are investigated via a systematic model extraction routine, and for the first time a fully monolithic AlGaN/GaN HEMT-based low noise amplifier (LNA) is reported. The monolithic microwave integrated circuit (MMIC) demonstrated a noise figure of 3.5 dB, gain of 7.5 dB, input return loss of -7.5 dB, and output return loss of -15 dB at 8.5 GHz. The MMIC was fabricated on layers grown by MOCVD on a silicon carbide substrate and employed a 0.25-mum x 150-mum AlGaN/GaN HEMT. These results demonstrate the potential for the integration of a robust low noise amplifier with an ultra-high performance power amplifier in a single GaN-based technology for next-generation military and communication systems.
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