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Proceedings Paper

Quantum 1/f noise in GaN FETs, HFETs, MODFETs, and their oscillators' phase noise
Author(s): Peter H. Handel; Amanda M. Hall; Hadis Morkoç
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Paper Abstract

GaN-based FETs, HFETs and MODFETs are ideally suited for use in high-power amplifiers and oscillators, due to their large band gap and high operating voltages. According to the quantum 1/f theory, the larger effective mass implied for the carriers also leads to lower fundamental 1/f noise and to lower resulting phase noise close to the carrier frequency. We have therefore studied the quantum 1/f noise sources in the channel and in the gate insulation. For the channel, a combination of conventional and coherent Quantum 1/f Effect (Q1/fE) is present, with the conventional Q1/fE dominant in the sub-threshold part of the channel toward the drain. It turns out that the quantum 1/f parameter "s" that determines the fraction of the two forms of Q1/fE, is no longer increasing proportionally to the width of the device w, when the latter exceeds the length of the channel. A logarithmic dependence on w is obtained for s instead. This is why an extremely large width w does not automatically lead to coherent Q1/fE in HFETs. Conventional Q1/fE applies for the gate insulation, with contributions of the much larger piezoelectric Q1/fE in spontaneously polarized AlGaN, if gate leakage is present. The noise figure is calculated, including all contributions. Finally, the minimal expected oscillator phase noise is calculated from the Q1/fE in the dissipative elements, even for perfectly linear amplifiers, by multiplication with the inverse fourth power of the quality factor, as was first done by us for quartz in 1979.

Paper Details

Date Published: 8 February 2007
PDF: 14 pages
Proc. SPIE 6473, Gallium Nitride Materials and Devices II, 64730O (8 February 2007); doi: 10.1117/12.703257
Show Author Affiliations
Peter H. Handel, Univ. of Missouri, St. Louis (United States)
Amanda M. Hall, Univ. of Missouri, St. Louis (United States)
Hadis Morkoç, Virginia Commonwealth Univ. (United States)


Published in SPIE Proceedings Vol. 6473:
Gallium Nitride Materials and Devices II
Hadis Morkoc; Cole W. Litton, Editor(s)

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