Switched Bandstop Filter with Low-Loss Linear-Phase Bypass

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional switched bandstop filters experience significant insertion loss due to signal-routing RF switches, especially when cascaded, and have discrepancies in passband group delay between all-pass and bandstop modes, which complicates the design and increases size.

Innovation Solution

The proposed solution involves locating switches outside the main signal path and using an all-pass network with SPDT switches, eliminating the need for signal-routing RF switches, thereby reducing insertion loss and minimizing passband group delay discrepancies without additional transmission line lengths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional switched bandstop filter configuration with signal-routing RF switches is used, then bandstop filtering function is achieved, but significant insertion loss occurs especially when multiple filters are cascaded

Engineering Contradiction:

Improveinsertion lossVSAvoidswitch configuration complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The invention extracts the switching function from the signal path by using a single switch to control coupling between resonators rather than using multiple signal-routing switches. This removes the source of insertion loss while maintaining the bandstop filtering capability through resonator coupling control.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The single switch controls the coupling state between multiple resonators, enabling one switching element to perform the function previously requiring multiple switches. This multi-functional approach reduces both insertion loss and device complexity simultaneously.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Length of stationary object

If traditional microwave bandstop filter topology with quarter-wavelength admittance inverters is used, then symmetric notch frequency response is achieved, but total through-line length becomes long for high-order filters

Engineering Contradiction:

Improvethrough-line lengthVSAvoidfrequency response symmetry

Core Design Contradiction:

Length of stationary objectVSManufacturing precision

Solution Approach 1:

The invention transitions from a linear through-line topology to a resonator coupling topology where filtering is achieved through the coupling state of resonators rather than through-line length. This dimensional change in filter architecture enables compact high-order filters while maintaining frequency response symmetry.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If reconfigurable bandstop filter with bypass capability is implemented using two signal-routing RF switches, then frequency agility is achieved, but considerable insertion loss occurs when multiple switched filters are cascaded

Engineering Contradiction:

Improvefrequency agilityVSAvoidinsertion loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The filter uses a single switch to control its own coupling state between resonators, eliminating the need for separate bypass switches. This self-service approach maintains frequency agility while minimizing insertion loss by reducing the number of switching elements in the signal path.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS10056662B2Switched bandstop filter with low-loss linear-phase bypass state

Publication Date: 2018.08.21 THE GOVERNMENT OF THE UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARY DEPARTMENT OF HEALTH & HUMAN SERVICES

AI summary

Systems and methods are provided for implementing a switched microwave bandstop filter with minimum insertion loss and phase distortion in the bypass state. For example, embodiments of the present disclosure provide systems and methods for implementing self-switching bandstop filters that do not require signal-routing RF switches, allowing for very low passband insertion loss and improved power handling.