High-Performance MMIC Inductors for GaN-on-Low-Resistivity Silicon for Microwave Applications

• Published in: IEEE microwave and wireless components letters Vol. 28; no. 2; pp. 99 - 101
• Main Authors: Eblabla, A., Li, X., Wallis, D. J., Guiney, I., Elgaid, K.
• Format: Journal Article
• Language: English
• Published: IEEE 01.02.2018
• Subjects: Benzocyclobutene (BCB); GaN-based high-electron-mobility transistors (HEMTs); high-<italic xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">Q Inductors; Inductance; Inductors; Integrated circuit modeling; low-resistivity silicon substrates; millimeter wave; Q-factor; Silicon; Spirals; Substrates
• ISSN: 1531-1309; 1558-1764
• DOI: 10.1109/LMWC.2018.2790705

Novel MMIC spiral inductors on GaN-on-low-resistivity silicon (LR-Si) substrates (<inline-formula> <tex-math notation="LaTeX">\sigma < 40~\Omega \cdot \text {cm} </tex-math></inline-formula>) are demonstrated with enhanced self-resonance frequency (<inline-formula> <tex-math notation="LaTeX">f_{\mathrm{ SRF}} </tex-math></inline-formula>) and <inline-formula> <tex-math notation="LaTeX">Q </tex-math></inline-formula>-factor. The developed technology improves inductor performance by suppressing substrate coupling effects using air-bridge technology above benzocyclobutene dielectric as an interface layer on the lossy substrate. A 0.83-nH spiral inductor with peak <inline-formula> <tex-math notation="LaTeX">Q </tex-math></inline-formula>-factor enhancement of 57% (<inline-formula> <tex-math notation="LaTeX">Q = 22 </tex-math></inline-formula> at 24 GHz) and maximum <inline-formula> <tex-math notation="LaTeX">f_{\mathrm{ SRF}} </tex-math></inline-formula> of 59 GHz was achieved because of the extra 5-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> elevation in air. An accurate broad-band model for the fabricated inductors has been developed and verified for further performance analysis up to 40 GHz. The proposed inductors utilize cost-effective, reliable, and MMIC-compatible technology for the realization of high-performance RF GaN-on-LR Si MMIC circuits for millimeter-wave applications.