Optically Isolated MEMS Switches for High-Voltage Control

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Solution Overview

Problem

Existing microelectromechanical systems (MEMS) switches require high-voltage sources for actuating, which can damage receiving electronic devices and complicate circuits, and they lack effective isolation from high-voltage signals and power supplies.

Innovation Solution

The implementation of optically isolated MEMS switches using an optical isolator and a MEMS switch, where the optical isolator generates high voltages between 20V and 10000V to control the MEMS switch, eliminating the need for high-voltage sources and enabling galvanic isolation between electronic devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If high-voltage sources are used to actuate MEMS switches, then the MEMS switch can be controlled, but the receiving electronic devices can be damaged and circuit complexity increases

Engineering Contradiction:

ImproveMEMS switch controlVSAvoiddamage to receiving electronic devices

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

An optical intermediary (light source and photodetector) is introduced between the control circuit and the MEMS switch. The light source converts electrical control signals to optical signals, which pass through the MEMS switch aperture to control the switch state without requiring direct electrical connection to the high-voltage switch terminals, thus protecting the control circuit from high-voltage damage

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The electrical control system is replaced with an optical control system. Instead of using electrical fields to control the MEMS switch directly, optical signals are used to trigger photodetectors that generate control voltages, substituting the mechanical/electrical control path with an optical one to eliminate harmful electrical connections

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If high-voltage sources are used to actuate MEMS switches, then the MEMS switch can be controlled, but circuit complexity increases

Engineering Contradiction:

ImproveMEMS switch controlVSAvoidcircuit complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The high-voltage generation function is extracted from the control circuit and relocated to the photodetector stage. The photodetectors directly convert optical signals into the high voltages needed for MEMS switch actuation, eliminating the need for separate high-voltage power supply circuits, charge pumps, and voltage multiplication stages in the control path

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If optical isolator is used to generate high voltages, then galvanic isolation is achieved, but the system requires optical components

Engineering Contradiction:

Improveisolation from high-voltage signalsVSAvoidsystem structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The optical isolation function and high-voltage generation function are merged into a single integrated photodetector array. The photodetectors simultaneously achieve galvanic isolation by using optical signals and generate the required high voltages through their photoelectric conversion capability, eliminating the need for separate isolation components and high-voltage generation circuits

Inventive Principle:

Principle #5Merging (Combining)

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

This solution provides robust isolation against voltage surges, reduces circuit complexity, and prevents damage to electronic devices by using internally generated voltages that do not propagate to the load, enhancing signal integrity and reducing noise.

Implementation Method 1

an optical receiver coupled to the control terminal of the switch, the optical receiver being configured to output, in response to receiving an optical signal, a voltage that is between 20V and 10000V

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentUS11228310B2System comprising a package having optically isolated micromachined (MEMS) switches with a conduit to route optical signal to an optical receiver and related methods

Publication Date: 2022.01.18 ANALOG DEVICES GLOBAL UNLTD

AI summary

Optically isolated micromachined (MEMS) switches and related methods are described. The optically isolated MEMS switches described herein may be used to provide isolation between electronic devices. For example, the optically isolated MEMS switches of the types described herein can enable the use of separate grounds between the receiving electronic device and the control circuitry. Isolation of high-voltage signals and high-voltage power supplies can be achieved by using an optical isolator and a MEMS switch, where the optical isolator controls the state of the MEMS switch. In some embodiments, utilizing optical isolators to provide high voltages, the need for electric high-voltage sources such as high-voltage power supplies and charge pumps may be removed, thus removing the cause of potential damage to the receiving electronic device. In one example, the optical isolator and the MEMS switch may be co-packaged on the same substrate.