A viscoelastic-aware experimentally-derived model for analog RF MEMS varactors

In this paper we present, for the first time, an experimentally-extracted model for the spring constant and tuning range of an analog RF-MEMS varactor that includes viscoelastic effects in RF-MEMS devices. By utilizing a bi-state bias condition with one state lasting 60 minutes and the other 1 minute, this model focuses on capturing the true electromechanical behavior of the varactor. An experimental setup with very high long-term accuracy is created to measure capacitance of the varactor up to 1,370 hours. The impact of these effects and the effectiveness of the model are demonstrated on a tunable-resonator loaded with RF-MEMS varactors.