MEMS Transfer Switches for RF Front-End Sensitivity

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Solution Overview

Problem

Radio frequency (RF) front-end devices face challenges with additive noise and protecting sensitive components from high power RF signals, which existing technologies address inadequately.

Innovation Solution

The implementation of micro-electro-mechanical systems (MEMS) transfer switches with parallel switch inputs and outputs, coupled with banks of signal conditioning devices, to condition wideband RF signals and improve frequency selection sensitivity, using a CTE-matching layer for thermal management and heat dissipation in printed wiring boards.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional RF front-end protection components are used, then sensitivity is improved, but insertion loss increases and power handling capability deteriorates

Engineering Contradiction:

Improvereceiver sensitivityVSAvoidinsertion loss

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The patent replaces traditional electronic protection components (limiters, switches, LNAs) with a MEMS-based mechanical switching system. The MEMS transfer switch uses movable mechanical contacts to route RF signals, providing protection and signal conditioning functions with lower insertion loss and better power handling than electronic components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces MEMS transfer switches as intermediary components between the RF signal source and the receiver front-end. These switches act as mediators that can selectively connect different signal paths, providing both protection and signal conditioning while maintaining low insertion loss through their high-quality mechanical contact design.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If high power RF protection is implemented, then component protection is improved, but noise figure deteriorates

Engineering Contradiction:

Improvecomponent protectionVSAvoidnoise figure

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent implements preliminary protection by placing MEMS transfer switches at the front-end of the receiver before sensitive components. These switches can be activated in advance to protect downstream components from high power RF signals, preventing damage before it occurs and maintaining optimal noise figures by keeping protection components in their default low-loss state.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces electronic protection mechanisms that add noise with mechanical MEMS switches that provide protection through physical isolation. The mechanical nature of MEMS switches allows them to handle high power signals without adding significant noise, unlike electronic limiters and protection circuits.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If wideband signal conditioning is implemented, then frequency selection sensitivity is improved, but device complexity increases

Engineering Contradiction:

Improvefrequency selection sensitivityVSAvoidsignal conditioning complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the wideband signal conditioning function into multiple independent banks of narrowband filters. Each bank handles a specific frequency range, and MEMS transfer switches selectively connect appropriate filter banks to the signal path. This segmentation allows precise frequency selection while managing complexity through modular architecture.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic signal conditioning by using controllable MEMS transfer switches to reconfigure the filter banks in real-time. The system can dynamically select and switch between different narrowband filters based on the desired frequency, providing adaptive frequency selection sensitivity without requiring a completely reconfigured hardware system.

Inventive Principle:

Principle #15Dynamics

4Adaptability or versatility

If multiple signal conditioning paths are provided, then signal conditioning capability is improved, but manufacturing cost increases

Engineering Contradiction:

Improvesignal conditioning capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent designs the MEMS transfer switches and filter banks to serve multiple functions simultaneously. The same MEMS switches used for signal routing also provide protection functions, and the filter banks serve both signal conditioning and frequency selection purposes. This multi-functionality reduces the need for separate dedicated components, lowering manufacturing costs while maintaining versatile signal conditioning capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 reduces noise figure and increases receiver sensitivity, enabling the RF front-end to handle high RF power levels with reduced insertion loss and mechanical stresses, while maintaining cost-effectiveness and flexibility in switching configurations.

Implementation Method 1

A front-end of a receiver has challenges with additive noise of the electronics and protecting sensitive components from damage by high power RF signals. The solution has been to provide some front-end protection (e.g., RF limiter) and utilize the best available Monolithic Microwave Integrated Circuits (MMIC) components (e.g., switches and low noise amplifier (LNA))

Methodology Applied

Scientific EffectMEMS (Micro-electro-mechanical systems): Microelectromechanical Systems

Implementation Method 2

Methodology Applied

Scientific EffectCTE-matching (Coefficient of Thermal Expansion matching): Thermal Expansion

Data Source

PatentUS10218397B1Sensitivity radio frequency (RF) receiver front-end using MEMS switches, RF communications device and method

Publication Date: 2019.02.26 LOCKHEED MARTIN CORP

AI summary

A radio frequency (RF) front end device is disclosed. The device comprises a plurality of micro-electro-mechanical system (MEMS) transfer switches having a plurality of parallel switch inputs and parallel switch outputs. The device comprises a plurality of banks of a plurality of parallel signal conditioning devices and each bank comprising a plurality of parallel paths having an input side and an output side, at least two of the banks of the plurality of signal conditioning devices couple the input side to the plurality of parallel switch outputs of a preceding MEMS transfer switch and the output side to the plurality of parallel switch inputs of a succeeding MEMS transfer switch. The MEMS transfer switches are controlled to condition a wideband signal through a selected set of signal conditioning devices to improve selection sensitivity of at least one frequency in a wideband. A method and RF communications device are also disclosed.