Envelope Detection Based Transition Time Supervision for Online Testing of RF MEMS Switches

This paper introduces a new method combining low frequency actuation signal as test stimuli and envelope detection on the RF (radiofrequency) output signal to provide a low cost mean for offline as well as for online testing of RF MEMS switches. The study includes the modelling of RF MEMS switches as well as some ideas how to test online and diagnose their functionality. The proposed approach uses the principle of alternate test that replaces conventional specification-based testing procedures, which require sophisticated test equipment and are time consuming. The basic idea is to use the actuation signal as a low frequency online test stimuli to the RF device. The low frequency characteristics measured from the envelope of component response are utilized in a regression process to predict the RF conventional specifications parameters like s-parameters. In the context of our online testing scheme, on and off transition time estimated from the output low frequency envelope are used as test metrics and are concurrently updated using recursive algorithms. Preliminary validation results obtained on a capacitive RF switch are very encouraging.