A.J. Green

  • 3.1 Demonstration of X-band T/R MMIC using AFRL AlGaN/GaN MMIC Process

    James Gillespie, Air Force Research Laboratory
    Kelson Chabak, Air Force Research Laboratory, Sensors Directorate
    Antonio Crespo, Air Force Research Laboratory, Sensors Directorate
    Robert Fitch, AFRL
    Darren Ferwalt, Cobham Advanced Electronic Systems
    David Frey, Cobham Advanced Electronic Systems
    Jeremy Gassmann, Cobham Advanced Electronic Systems
    Mark Walker, Cobham Advanced Electronic Solutions
    Ryan Gilbert, Wyle Laboratories
    Dennis Walker Jr, Air Force Research Laboatory, Sensors Directorate
    Glen Via, AFRL
    A.J. Green
    K.D. Leedy
    R.K. Mongia
    B.S. Poling
    K.A. Sutherlin
    S.E. Tetlak
    J.P. Theimer
    G.H. Jessen
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  • 4A.2 – Temperature Effects on DC and RF Characteristics of 140 nm AlGaN/GaN HEMTs with Regrown Contacts

    B. K. Sarker, KBR, Inc.
    Nicholas P. Sepelak, KBR, Air Force Research Laboratory Sensors Directorate, WPAFB, OH, USA
    D.E. Walker Jr. , Sensor Electronic Technology
    K. Nishimura, KBR, Air Force Research Laboratory Sensors Directorate, WPAFB, OH, USA
    A. Crespo, Air Force Research Laboratory, Sensors Directorate
    Gary Hughes, Air Force Research Laboratory, Sensors Directorate, Wright-Patterson AFB, OH
    A.J. Green
    A. Islam, Air Force Research Laboratory

    4A.2 Final.2025

    Abstract
    We conducted DC and small-signal RF characterization on AlGaN/GaN high-electron-mobility transistors (HEMTs) over a range of temperatures to examine temperature-dependent variations in key device performance metrics including transconductance (gm), extrinsic cutoff frequency (fT), maximum gain frequency (fmax), unilateral power gain (UPG), and maximum stable gain (MSG). Our findings indicate that device parameters decline with increasing temperature at a distinct rate. Specifically, a 100°C rise results in fT and fmax dropping by about 8 GHz and 17 GHz, respectively, while MSG decreases by approximately 1 dB. These changes are inherent to the device physics and are not influenced by its geometry or operational mode.