An RF MEMS Variable Capacitor with Intelligent Bipolar Actuation

We propose an IBA scheme based on a pull-out detection, which is suitable for implementing in a circuit. The scheme is implemented in a driver IC that is part of a module with an RF MEMS variable capacitor. No failures are observed over 10⁸ cycles at 85degC, which is an accelerated charging condition.

RF MEMS capacitive devices, with their low loss and excellent linearity, are regarded as key devices for reconfigurable RF front-ends. To date however, the adoption of such devices in mobile handsets has been prevented by reliability issues. One of the major reliability issues is the dielectric charging inherent in electrostatic actuators [1]. Intelligent bipolar actuation (lBA), reported previously, has shown potential as a means to prevent the charging [2]. The instrument-based IBA approach, however, cannot be implemented in a circuit because of the time consuming charge detection process. We propose an IBA scheme based on a pull-out detection, which is suitable for implementing in a circuit. The scheme is implemented in a driver IC that is part of a module with an RF MEMS variable capacitor. No failures are observed over 10⁸ cycles at 85°C, which is an accelerated charging condition.