Integration of BaxSr1-xTiO3 thin films with AlGaN/GaN HEMT circuits

AlGaN/GaN HEMTs have attracted considerable interest as power devices in microwave applications, promising greater than a tenfold increase in power-density as compared with GaAs devices. Similarly, Ba_xSr_1-xTiO₃ (BST) thin films have been investigated for microwave circuit application because of their high dielectric constants, high tunability, relatively low loss, and fast switching speed. BST-based varactors are especially attractive for high power RF circuits since they can sustain relatively large AC fields, unlike diode technologies. Additionally due to its high dielectric constant, BST is a candidate for every compact MMIC DC blocking capacitors, promising a 100-fold reduction in capacitor area as compared with SiN and SiO₂ capacitors. In this paper, we will provide a valid method of process integration for future active GaN circuit design and fabrication using BST capacitors. A C-band MMIC oscillator in GaN HEMT technology has been designed with BST capacitors as DC blocking capacitors.