MEMS Shuttle Switch for RF Signal Steering

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Solution Overview

Problem

Existing MEMS switches face challenges in achieving low loss and high isolation over a wide range of frequencies, particularly in miniaturized communication systems, due to stringent size, weight, and power constraints, and require innovative designs for effective implementation in broadband communications.

Innovation Solution

A bi-directional MEMS switch design featuring a shuttle with resilient support and a drive portion that moves along a motion axis in response to voltage, utilizing interdigitated fingers to form electrical connections between a common contact and terminal contacts, allowing for selective routing of RF signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If miniaturized switches (MMIC and MEMS) are used to meet size constraints, then device size is reduced, but achieving low loss and high isolation over wide frequency range becomes more difficult

Engineering Contradiction:

Improveswitch sizeVSAvoidlow loss and high isolation performance

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent employs a movable shuttle structure that can dynamically switch between different contact positions (first contact, second contact, or floating). This dynamic configuration allows the compact switch to achieve multiple isolation states and maintain low loss performance across wide frequency ranges by optimizing the electrical connection path based on operating conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The switch design incorporates variable electrical parameters through the movable shuttle that can change its position and connection state. By changing the physical position of the shuttle along the motion axis, the electrical characteristics (loss, isolation, frequency response) are dynamically adjusted to meet performance requirements across different operating frequencies.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the shuttle is electrically isolated from the substrate, then RF signal integrity is improved, but manufacturing complexity increases

Engineering Contradiction:

ImproveRF signal integrityVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces complex mechanical isolation structures with electrostatic suspension and capacitive coupling mechanisms. The shuttle is electrically isolated from the substrate through dielectric layers and air gaps, while still maintaining controllable mechanical position through electrostatic forces. This substitution simplifies the manufacturing process by eliminating the need for complex mechanical support structures.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Speed

If resilient members are used to support the shuttle, then switching speed is improved, but device complexity increases

Engineering Contradiction:

Improveswitching speedVSAvoidswitch structure complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The resilient members provide self-restoring force to the shuttle, enabling automatic return to the default position after actuation. This self-service mechanism eliminates the need for additional reset mechanisms or control circuits, simplifying the overall device complexity while maintaining fast switching speeds through the elastic recovery of the resilient members.

Inventive Principle:

Principle #25Self-service

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 enables efficient and reliable switching of RF signals with low loss and high isolation across a wide frequency range, meeting the stringent requirements of miniaturized communication systems by providing a compact and efficient switching mechanism.

Implementation Method 1

The drive portion is configured to selectively move the shuttle along a motion axis aligned with the elongated length in response to an applied voltage

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Implementation Method 2

A shuttle having an elongated length extends over the substrate and is resiliently supported at opposing first and second ends thereof by the first and second resilient members respectively

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS9123493B2Microelectromechanical switches for steering of RF signals

Publication Date: 2015.09.01 HARRIS CORP

AI summary

A switch includes a shuttle having an elongated length resiliently supported at opposing ends thereof and configured to move along a motion axis in response to an applied voltage. A shuttle switch portion includes a plurality of shuttle contact fingers extending transversely from opposing sides of the shuttle. A common contact at a common terminal side of the shuttle includes a plurality of contact fingers respectively interdigitated with the shuttle contact fingers. First and second terminal contacts are adjacent a switched terminal side of the shuttle, and include first terminal contact fingers and second terminal contact fingers respectively interdigitated with shuttle contact fingers. The shuttle switch portion is configured to selectively connect the common contact to the first terminal contact or the second terminal contact.