Switchable Frequency Filter Using Radial Stubs and Electronic Switching

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Solution Overview

Problem

Existing switchable filters for high-frequency signals in the gigahertz range face challenges with high power consumption limitations, sensitivity to parasitic effects, and large signal requirements, which affect the filter's performance and space efficiency.

Innovation Solution

A changeover filter design that uses electronically controllable switching elements and radial stubs to adjust cut-off frequencies, minimizing parasitic effects and allowing for high power consumption without being limited by switching element constraints, while maintaining a compact form factor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a filter bank with several filters and switches is used to achieve switchable frequency bands, then the cut-off frequency can be adjusted, but the space requirement becomes large

Engineering Contradiction:

Improveswitchable frequency bandsVSAvoidspace requirement

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent merges multiple filter functions into a single filter structure by combining multiple resonator circuits (first, second, and third resonator circuits) that can be selectively activated. Instead of using separate physical filters for different frequency bands, the invention integrates them within one filter housing with shared components, thereby reducing the overall space requirement while maintaining the ability to switch between different frequency bands.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single filter structure is designed to perform multiple filtering functions across different frequency bands. The filter incorporates switchable resonator circuits that can be activated in different combinations to achieve various cut-off frequencies and filtering characteristics, making the filter universal for multiple applications without requiring separate dedicated filters for each frequency band.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If switches are used to select different frequency bands in a filter bank, then the desired frequency can be addressed, but the payload signal is strongly attenuated

Engineering Contradiction:

Improvefrequency band selectionVSAvoidsignal attenuation

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent replaces traditional mechanical or simple electronic switches with electronically controllable switching elements that have lower parasitic effects. These switching elements are integrated directly into the resonator circuits, allowing for smoother transitions and better signal preservation when switching between different frequency bands, thereby reducing payload signal attenuation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the electrical parameters of the filter circuits dynamically by adjusting the switching states of the resonator circuits. By changing the configuration of capacitive and inductive elements through electronic switching, the filter can adapt its characteristics without introducing significant signal loss, maintaining better signal integrity across different frequency selections.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If switches with high current consumption are used for filter switching, then frequency bands can be switched, but the overall power consumption is limited by the maximal current consumption of the switch

Engineering Contradiction:

Improvefilter switching capabilityVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent employs switching elements that are optimized for high-frequency operation with low power consumption characteristics. These switching elements are designed to operate efficiently in the gigahertz range, consuming minimal power during switching operations, thereby enabling frequent frequency band switching without being constrained by high power consumption limits.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Ease of manufacture

If conventional switching topologies are used, then filtering can be implemented, but large reverse voltages occur in switching diodes limiting power consumption

Engineering Contradiction:

Improvefilter implementationVSAvoidpower consumption limit

Core Design Contradiction:

Ease of manufactureVSPower

Solution Approach 1:

The patent introduces intermediate circuit elements and optimized switching topologies that mediate between the signal path and the switching elements. This intermediary structure distributes and manages the voltage stress, preventing large reverse voltages from concentrating on individual switching diodes. The design includes voltage distribution networks and protective circuitry that enable the use of lower breakdown voltage diodes while maintaining proper filtering functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9825623B2Switchable frequency filter

Publication Date: 2017.11.21 ROHDE & SCHWARZ GMBH & CO KG

AI summary

The invention relates to a filter, for example, a switchable harmonic filter for the gigahertz range. A first line segment, which can comprise a radial stub leads away from a main line of the filter. A second line segment can be electrically connected to the first line segment. At least two electronically controllable switching elements are provided, by means of which the first and the second line segment can be connected.