Spring-constant measurement methods for RF-MEMS capacitive switches

Abstract

In this article we compare three approaches to measure the spring constant in RF MEMS capacitive switches. We use the lowest vibration mode, as obtained from vibrometry; the pull-in voltage; and the low-field capacitance-voltage curve of the device to extract the spring constant. Experimental results are presented for each approach, and FEM model predictions are used to further verify and interpret the findings. Pros and cons of each method are discussed.