Matched Duplexer and Multiband Filter Layout for Lower RF Loss

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Solution Overview

Problem

Existing duplexer and multiplexer designs introduce extra loss and large size due to long PCB-based transmission lines, making it difficult to meet low-level Tx path loss requirements and increasing manufacturing costs for dual-band and multiband filters.

Innovation Solution

Implementing single-port-matched band pass filters (SPMBPF) and dual-port-matched band pass filters (DPMBPF) with integrated impedance matching, using the same materials and manufacturing processes to reduce transmission line length and enhance impedance matching, thereby reducing losses and size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If carrier PCB and long transmission lines are used to combine filters, then impedance matching is achieved, but transmission loss increases and size increases

Engineering Contradiction:

Improvetransmission lossVSAvoidtransmission line length

Core Design Contradiction:

Loss of energyVSLength of stationary object

Solution Approach 1:

The patent combines the filter structure and impedance matching function into a single integrated filter assembly. The matching structure is directly coupled to the filter ports, eliminating the need for separate long transmission lines on carrier PCB. This merging of functions reduces the overall length of transmission paths and minimizes transmission loss while maintaining impedance matching performance.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts the impedance matching function from the carrier PCB transmission lines and integrates it directly into the filter assembly. By taking out the matching function and combining it with the filter structure, the design eliminates long lossy transmission lines while preserving the impedance matching capability through the integrated matching structure.

Inventive Principle:

Principle #2Taking out (Extraction)

2Loss of energy

If carrier PCB and long transmission lines are used to combine filters, then impedance matching is achieved, but device size increases

Engineering Contradiction:

Improvetransmission lossVSAvoiddevice size

Core Design Contradiction:

Loss of energyVSArea of stationary object

Solution Approach 1:

The patent merges the filter and impedance matching functions into a single compact filter assembly. The matching structure is directly coupled to the filter ports without requiring separate carrier PCB and long transmission lines. This integration significantly reduces the overall device footprint and area while maintaining the necessary impedance matching performance.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If multiple single-band filters and transmission lines are used for dual-band/multiband filter, then band selection is achieved, but manufacturing complexity increases

Engineering Contradiction:

Improveband selection capabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent segments the dual-band/multiband filter into multiple single-band filter assemblies, where each assembly includes a filter structure and integrated impedance matching structure. Each segment is designed and manufactured independently with its matching function built-in, simplifying the overall manufacturing process compared to traditional approaches requiring separate matching networks for each band.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent combines multiple single-band filter assemblies with integrated matching structures to form a dual-band/multiband filter system. By merging the matching function into each filter assembly, the design simplifies manufacturing while maintaining the ability to select multiple bands, reducing the complexity associated with traditional separate matching networks.

Inventive Principle:

Principle #5Merging (Combining)

4Adaptability or versatility

If traditional dual-band/multiband filter designs are used, then band filtering is achieved, but filter tuning difficulty increases

Engineering Contradiction:

Improvemulti-band operationVSAvoidfilter tuning difficulty

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent segments the multi-band filter into independent single-band filter assemblies, each with its own integrated matching structure. This segmentation allows each assembly to be tuned and adjusted independently, significantly reducing the tuning difficulty compared to traditional integrated multi-band filters where adjustments in one band affect other bands.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by providing dedicated impedance matching structures for each filter port and band. Each matching structure is optimized for its specific band and port, allowing independent adjustment and tuning without affecting other bands. This localized approach simplifies the tuning process while maintaining multi-band operation capability.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS12592723B2Duplexer, multiplexer and multiband filter

Publication Date: 2026.03.31 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

Methods and apparatuses are provided for a matched band pass filter utilized in a duplexer or multiplexer. In one embodiment, the matched band pass filter includes a filter part and a port-matching part that is coupled to and in signal communication with the filter part. The filter part is configured to filter an RF signal and includes an input port. The port-matching part includes an output port. The port-matching part is configured to provide impedance matching through the output port.