Real-time monitoring and characterization of RF MEMS switches and MEMS varactors using capacitive sensor interface.

摘要

RF Microelectromechanical systems (MEMS) have evolved greatly in the last two decades for their superior performance compared to their conventional counterparts. The reliability and life time performance for those devices are vital issues especially if we consider sensitive high power applications for which those devices are made. However, reliability issues and life time performance are still under question for those devices. The bouncing of an RF MEMS switch during its operation is one of the main problems that shortens the lifetime of the device and degrades its performance. MEMS varactors also suffer from variations on their parameters with time.;To improve the performance of those devices, a close-up monitoring needs to be conducted during their operation, and possibly real-time monitoring using integrated reader. The collected information can lead to characterizing the device and prognostication of failures. Monitoring and testing these devices for reliability and characterization is usually performed using expensive equipments (eg. laser Doppler vibrometer) that require special setups and sometimes limited performance when it comes to real-time monitoring, hermeticity and packaged testing.;In this work, we propose a simplified technique for real time electronic monitoring for MEMS that operates without interfering with the device's operation and requires no special setup. Consuming a minuscule amount of power and having a small size, the sensing circuit can be placed on the same wafer as the MEMS device without affecting its operation. This technique uses a capacitance sensor interface that measures the capacitance of the device, hence being able to monitor the motion or any degradation on the performance of device.