Anchorless electrostatically activated micro electromechanical system switch

Abstract

A micro electromechanical system (MEMS) switch (10) includes a substrate (12) and a stress free beam (14) disposed above the substrate (12). The stress free beam (14) is provided within first and second platforms (16, 18) to limit displacement of the stress free beam (14) in directions that are not substantially parallel to the substrate (12). A set of one or more control pads (20) is disposed in a vicinity of a first lengthwise side (22) of the stress free beam (14) for creating a potential on the first lengthwise side (22) of the stress free beam (14). The stress free beam (14) is displaceable in directions substantially parallel to the substrate (12) in accordance with the potential for providing a signal path.

Description

FIELD OF THE INVENTION [0001] The present invention relates generally to switches and, more specifically, to switches implemented by Micro Electromechanical System (MEMS) technology. BACKGROUND [0002] Micro Electromechanical System (MEMS) switches are widely used in RF communication systems such as, for example, phased array antennas, phase shifters, switchable tuning elements, and radar sensors. Generally, MEMS switches have features such as low insertion loss, low power consumption, low cost, small size, wide bandwidth operation, long lifetimes and fast switching speeds not found in conventional solid state switches (e.g., FETs or PIN diodes). Specifically, a high quality MEMS switch should ideally have as many of the following features as possible: low activation voltage, high switching speed, long operation lifetime, good isolation from the output signal during an OFF state, low contact resistance and high contact force between the contact electrodes during an ON state, little o...

AI Technical Summary

Benefits of technology

[0008] Accordingly, the present invention provides a micro electromechanical system (MEMS) switch that includes a substrate and a stress free beam disposed above the substrate. The stress free beam is provided within first and second platforms. The first and second platforms are disposed on the substrate and limit displacement of the stress free beam in directions that are not substantially parallel to the substrate. The MEMS switch also includes a first set of one or more control pads disposed in a vicinit

Problems solved by technology

However, none of the conventional switches exhibit all of the above features.

However, electrostatic switches also have several disadvantages such as slow switching speed (on the order of psec to msec), relatively high actuation voltage (10-80 V), stiction problems when the contact electrodes are welded together upon physical contact, relatively short lifetimes (100 million cycles for cold switching), and instability problems due to thermal and fabrication related stresses.

Images