High-Q inductors and low-loss bandpass filters on Al2O3 substrates by thin-film technology

Abstract

High-Q spiral inductors were designed and fabricated on high-resistivity Al2O3 substrates with an air-bridge technology. A maximum Q-value of 36 was achieved for a 2.74 nH inductor at 2.5– 5.5 GHz. Detailed broadband models for inductors and interdigital capacitors have been developed based on measured results, which enable us to build a low insertion loss 2.4 GHz bandpass filter with a size of 2 mm×2 mm. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 20: 322–326, 1999.