Radio Frequency (RF) Filter Tuning Element

To meet the requirements of the AF18A-T015 solicitation, MaXentric and University of California San Diego are proposing the development of a low loss, high linearity capacitor. The tunable capacitor target is a compact integrated design, capable of a tuning range up to 4:1, with a minimum Q of 80 at 4 GHz, and handling up to 20W CW. During phase I, UCSD studied a novel varactor structure to improve the high performance GaN varactors previously demonstrated. Experimental large area GaN on QST and GaN on GaN mesa diodes during Phase I have shown excellent performance reducing leakage as expected, with high yield and reproducible as-designed C-V characteristics. Switched bank of capacitors using GaN MMIC process have been studied by MaXentric. Trade-off results between Q, power handling, and tuning range have been studied. Depending on the targeted applications, the varactor alone or assisted by a switched bank of capacitors can be used. During Phase II, the team will fabricate varactors with appropriately narrow fin geometries, and provide tunable capacitors that will have a wide range of possible applications. Specific demonstrations will be done in band-pass or band-stop filters.