MEMS Switch Protection via Controllable Shunt Path
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Solution Overview
Problem
MEMS switches face damage and performance degradation when switched with voltage across them or current flowing through them, leading to arcing and permanent conductivity or open circuits, limiting their application range.
Innovation Solution
A controllable shunt path is provided in parallel with the MEMS switch, comprising a solid-state switch and a mechanical switch, which can disconnect the solid-state switch when not needed, and includes components like resistors, transistors, and inductors to manage voltage and current, reducing parasitic components and signal propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid state switch is continuously connected in parallel with the MEMS switch to provide protection, then the MEMS switch is protected during opening and closing operations, but parasitic capacitance increases and off-state performance deteriorates
Solution Approach 1:
The patent applies dynamics by making the shunt path dynamically controllable through a mechanical switch that opens/closes based on the operational state of the MEMS switch. During MEMS switching operations, the mechanical switch closes to activate the solid state switch protection path. During normal operation, the mechanical switch opens to disconnect the solid state switch and eliminate parasitic capacitance. This dynamic configuration resolves the contradiction between needing protection (reliability) and minimizing parasitic effects (energy loss).
2Productivity
If the MEMS switch is operated with voltage across it or current flowing through it, then switching speed and productivity improve, but arcing occurs causing permanent damage to contacts
Solution Approach 1:
The patent applies preliminary action by providing a shunt path with a solid state switch that is activated in advance of or during the MEMS switch operation. When voltage or current is present across the MEMS switch, the solid state switch in the shunt path provides an alternative current path, preventing arcing at the MEMS contacts. This preliminary protective measure allows the MEMS switch to operate with voltage/current (improving productivity) without contact damage (maintaining reliability).
Data Source
AI summary
A method of and apparatus for protecting a MEMS switch is provided. The method and apparatus improve the integrity of MEMS switches by reducing their vulnerability to current flow through them during switching of the MEMS switch between on and off or vice versa. The protection circuit provides for a parallel path, known as a shunt, around the MEMS component. However, components within the shunt circuit can themselves be removed from the shunt when they are not required. This improves the electrical performance of the shunt when the switch is supposed to be in an off state.