A Wide Tuning Range MEMS Varactor Based on a Toggle Push-Pull Mechanism

This paper presents a novel wide tuning range MEMS varactor based on a toggle push-pull mechanism for high RF power applications and improved reliability. The device anchoring utilizes a torsion spring mechanism which virtually allows for a full capacitance tuning range. Improved mechanical stability is also provided by the actively controlled pull-out implementation that is realized without increasing the MEMS manufacturing complexity. As a proof of concept, a toggle MEMS varactor has been modeled, designed and manufactured in shunt configuration on a 50 coplanar transmission line. Analytical and full wave electromechanical models are provided as well as electromagnetic characterization. The device has been manufactured on HR Silicon substrate by using the standard FBK-irst RF MEMS process. Optical profile, DC and RF measurements are presented in the 0 - 40 GHz frequency band. Excellent RF performance as well as a capacitance tuning ratio of 2.5 has been obtained.