Hybrid RF Duplexer Coupling Air Cavity and Ceramic Waveguide Filters

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Solution Overview

Problem

Existing wireless communication systems face challenges in efficiently combining air cavity filters and ceramic waveguide filters for frequency division duplex applications due to differences in design, size, and materials, leading to additional losses and mismatched cable lengths, particularly in dual band duplexer structures.

Innovation Solution

Hybrid structures are developed that combine air cavity resonators with ceramic waveguide resonators, utilizing aligned windows and bridges to couple energy efficiently, with orthogonal orientations and varying heights to minimize unwanted coupling, and incorporating metal bridges for improved energy transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a low pass filter is used to reduce high frequency noise, then signal quality is improved, but group delay variation increases causing distortion

Engineering Contradiction:
Improvehigh frequency noiseVSAvoidgroup delay variation
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent combines a low pass filter and a high pass filter into a single hybrid filter structure. The low pass filter section removes high frequency noise while the high pass filter section compensates for group delay variation, achieving both noise reduction and distortion correction in one integrated device.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The hybrid filter uses composite filtering technology, combining different filter types (low pass and high pass) with complementary characteristics. This composite approach allows the filter to simultaneously achieve noise reduction and maintain signal integrity by leveraging the strengths of each filter type.

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If a high pass filter is used to reduce low frequency noise, then signal quality is improved, but attenuation at the pass band edge increases causing distortion

Engineering Contradiction:
Improvelow frequency noiseVSAvoidattenuation at pass band edge
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent merges a high pass filter and a low pass filter into a hybrid filter structure. The high pass filter section removes low frequency noise while the low pass filter section compensates for attenuation at the pass band edge, achieving both noise reduction and distortion correction.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The hybrid filter employs composite filtering by combining high pass and low pass filter sections. This composite structure enables the filter to simultaneously achieve low frequency noise reduction and maintain signal integrity by compensating for edge attenuation effects.

Inventive Principle:
Principle #40Composite materials

3Reliability

If noise reduction is applied to improve signal quality, then communication reliability is improved, but speech naturalness deteriorates due to signal distortion

Engineering Contradiction:
Improvecommunication reliabilityVSAvoidsignal distortion
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The hybrid filter combines noise reduction functionality with distortion compensation by integrating both low pass and high pass filter sections. This merged structure reduces noise to improve communication reliability while simultaneously correcting group delay variation and attenuation to maintain speech naturalness.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The composite hybrid filter structure integrates multiple filtering functions to achieve both noise reduction and distortion correction. By combining different filter types with complementary characteristics, the system improves communication reliability while preserving speech quality and naturalness.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP4315496B1Hybrid type filter solution
Publication Date: 2026.05.06 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP4315496B1 patent drawingFigure 1A~2B
  • EP4315496B1 patent drawingFigure 3
  • EP4315496B1 patent drawingFigure 4A~4C

AI summary

Hybrid structures, filters and duplexers are disclosed. According to one aspect, a radio frequency (RF) duplexer includes a common resonator coupled to at least one chamber of an air cavity filter, a first ceramic waveguide filter, CWGF, having a first opening in a first CWG wall of the first CWGF, the first opening at least partially aligned with a first window of the common resonator to couple energy between the common resonator and the CWGF, and a second CWGF having a second opening in a second CWG wall of the second CWGF, the second opening at least partially aligned with the second window of the common resonator to couple energy between the air cavity resonator and the CWGF.