A. Eblabla

Cardiff University

  • 3B.3 – Metal Additive Micro-Manufacturing to Achieve Enhanced Air-Bridge Geometry for Coplanar Waveguide mm-Wave GaN-on-SiC Integrated Circuits

    A. Collier, Cardiff University
    A. Eblabla, Cardiff University
    W. Sampson, Cardiff University
    E. Yadollahifarsi, Cardiff University
    E. Hepp, Exaddon AG
    R. Conte, Exaddon AG
    K. Elgaid, Exaddon AG

    3B.3 Final.2025

    Abstract
    This paper presents a novel cavity coplanar waveguide (CCPW) structure based on GaN-on-SiC technology for high-power microwave applications. The CCPW structure was fabricated using an emerging monolithic microwave integrated circuit (MMIC)-compatible localised electrodeposition metal additive micro-manufacturing (μAM) process, achieving an air-bridge height of 50 μm. Electromagnetic (EM) simulations revealed that introducing a cavity above the CPW improves impedance matching at mm-wave frequencies while providing a robust ground-return path. S-parameter measurements show that the CCPW provides a 6.5 dB improvement in reflection coefficient at 110 GHz compared to a standard coplanar waveguide (CPW) structure. Furthermore, both simulations and measurements indicate a broadband reflection coefficient trough suggesting the potential for broadband impedance matching in MMIC applications. To further analyse RF parasitics, a high-frequency equivalent circuit model was developed, demonstrating significant performance improvements of the CCPW compared to a printed air-bridge.

  • 4A.3 – Dual-Gate RF HEMT Based on P-GaN/AlGaN on Si Technology for Future X-Band On-Chip RF and Power Electronics

    A. Eblabla, Cardiff University
    W. Sampson, Cardiff University
    A. M. Bhat, Cardiff University
    A. Collier, Cardiff University
    E. Yadollahifarsi, Cardiff University
    K. Elgaid, Exaddon AG

    4A.3 Final.2025

    Abstract
    This paper presents dual-gate (2 × 0.5 μm) RF high electron mobility transistors (HEMTs) on P-GaN/AlGaN on Si substrate for next-generation airborne applications. The dual-gate architecture enhanced switching performance and reduced power loss, achieving a 77% reduction in off-state gate leakage current (0.3 mA/mm at VGS = -6V) and improving the ION/IOFF ratio by 1.9 orders of magnitude (5.45 × 10⁴) over single-gate devices. DC characterization revealed a current density (IDS) of 712 mA/mm, on-resistance (RON) of 3.12 Ω.mm, peak transconductance (GM) of 223 mS/mm, and pinch-off voltage (VP) of -2.4 V. S-parameter measurements showed a cut-off frequency (fT) of 7.12 GHz and a maximum oscillation frequency (fMAX) of 24.18 GHz. These results support the integration of the proposed RF devices with existing E-mode power devices on a single P-GaN/AlGaN HEMT on Si platform, paving the way for integrated transceiver modules.