High-power MEMS varactors and impedance tuners for millimeter-wave applications

A high-power contactless RF microelectromechanical system (MEMS) varactor and an impedance tuner that utilizes this varactor and is simultaneously optimized for maximum impedance coverage and power handling are presented in this paper. The proposed varactor can successfully handle 4 W of RF power (hot tuning) for more than 10⁸ cycles when tested with no hermetic packaging or nitrogen protection. This is the highest power handling under hot tuning conditions reported to date. In addition to this MEMS device, a 30-GHz four-varactor impedance tuner optimized for high-power operation is demonstrated. The power handling capability of this tuner is 4.5 times higher than conventional designs. These results experimentally demonstrate for the first time the significant advantages of contactless MEMS devices over contact-based structures (e.g., switches) for high-power applications.