Back-to-back MEMS Switches with Passive Elements
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Solution Overview
Problem
Conventional MEMS switches experience damage or failure due to dramatic state changes and energy transfer during opening and closing, especially in environments with strong electromagnetic fields, voltage surges, and fast transients, which reduces their reliability and performance.
Innovation Solution
A MEMS device with two switches in a back-to-back configuration and passive elements that reduce energy transfer during state transitions, providing high isolation and protecting the switches from voltage and current surges by sharing actuation voltage and using impedance varying passive elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MEMS switches are used to achieve high isolation and low on-resistance, then switching performance is improved, but energy transfer during state transitions causes damage or failure
Solution Approach 1:
The patent introduces an intermediary circuit configuration (back-to-back switch arrangement with passive elements) that mediates the energy transfer during state transitions. The passive elements (resistors, capacitors, or inductors) act as intermediaries to absorb or dissipate the harmful energy transfers, protecting the MEMS switches from damage while maintaining the desired high isolation and low on-resistance characteristics.
Solution Approach 2:
The patent segments the single MEMS switch into two MEMS switches arranged in a back-to-back configuration. This segmentation allows the system to maintain the beneficial electrical characteristics while distributing and managing the energy transfer effects across multiple components, reducing the stress on individual switches.
2Reliability
If power diverters and active circuits are used to reduce energy transfer, then MEMS switch protection is improved, but system cost and complexity increase
Solution Approach 1:
The patent uses passive elements as intermediaries that provide protection without requiring complex active control circuits. These passive components (resistors, capacitors, inductors) automatically manage energy transfer through their inherent electrical properties, eliminating the need for additional active protection circuits while maintaining simplicity and reliability.
Solution Approach 2:
The patent employs passive elements that are simple, inexpensive components compared to active protection circuits. These passive elements provide effective protection against energy transfer damage without requiring complex control logic or additional power consumption, offering a cost-effective solution for MEMS switch protection.
3Productivity
If gradient fields are used in MRI systems, then imaging capability is improved, but induced voltages on MR coils cause MEMS switch stress and failure
Solution Approach 1:
The patent introduces passive elements as intermediaries between the MR coil and the MEMS switches. These elements (particularly capacitors and inductors) serve to filter or block the high-frequency voltage spikes induced by gradient fields, allowing the MRI system to operate at full capability while protecting the MEMS switches from the harmful induced voltages.
Solution Approach 2:
The patent converts the harmful effect of induced voltages into a manageable condition by using passive elements that are specifically designed to handle these transient voltages. The same gradient fields that provide imaging capability also create the protective voltage distribution across the back-to-back switch configuration, with the passive elements ensuring that the induced voltages do not exceed the switches' operational limits.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly improves the reliability and lifespan of MEMS switches by reducing energy coupling across contacts, maintaining high isolation, and preventing self-actuation, especially in environments with strong electromagnetic interference.
Implementation Method 1
the gate driver employs electrostatic, magneto-static, piezoelectric and/or thermal designs for providing actuation forces
Implementation Method 2
the gate driver employs electrostatic, magneto-static, piezoelectric and/or thermal designs for providing actuation forces
Implementation Method 3
the gate driver employs electrostatic, magneto-static, piezoelectric and/or thermal designs for providing actuation forces
Implementation Method 4
the gate driver employs electrostatic, magneto-static, piezoelectric and/or thermal designs for providing actuation forces
Implementation Method 5
one or more passive elements coupled to one or more of the first and second MEMS switches, wherein the one or more passive elements reduce energy transfer during state transition of the MEMS device
Data Source
AI summary
A micro-electromechanical system (MEMS) device that in one embodiment includes at least two MEMS switches coupled to each other in a back-to-back configuration. The first and second suspended elements corresponding to first and second MEMS switches are electrically coupled. Further, first and second contacts corresponding to the first and second MEMS switches are configured such that a differential voltage between the second suspended element and the second contact is approximately equal to a differential voltage between the first suspended element and the first contact. The MEMS device includes at least one actuator coupled to one or more of the first and second suspended elements to actuate one or more of the first and the second suspended elements. In one example, the MEMS device includes one or more passive elements coupled to one or more of the first and second MEMS switches.