Multiplexer Filter Layout for Low-Loss Signal Isolation

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Solution Overview

Problem

Existing multiplexers suffer from degradation in transmission loss due to mismatched attenuation requirements between band pass filters, leading to excessive attenuation and increased loss in certain signal paths.

Innovation Solution

A multiplexer design that includes specific filter configurations, such as first, second, third, fourth, and fifth filters, each with distinct frequency band pass and attenuation characteristics, to ensure optimal isolation and reduced transmission loss across different signal paths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a high pass filter (HPF) is arranged on the signal path where a band pass filter (BPF) is arranged, then isolation between signals is improved, but transmission loss is degraded due to excessive attenuation

Engineering Contradiction:

Improveisolation between signalsVSAvoidtransmission loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent divides the attenuation function into two separate filters: a band pass filter (BPF) that provides primary attenuation for frequencies outside its pass band, and a band elimination filter (BEF) that provides additional attenuation specifically for the pass band of another filter. This segmentation allows each filter to be optimized for its specific function, preventing excessive attenuation in the BPF path while maintaining isolation through the BEF.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different filter characteristics to different signal paths based on local requirements. The BPF is designed with specific attenuation characteristics for its own pass band, while the BEF is strategically placed to provide targeted attenuation only where needed (in the pass band of another filter). This local quality approach ensures that attenuation is applied precisely where required without degrading transmission loss in paths where it is not needed.

Inventive Principle:

Principle #3Local quality

2Device complexity

If a band elimination filter (BEF) with low attenuation function is used, then device complexity is reduced, but isolation performance is insufficient requiring additional HPF

Engineering Contradiction:

Improvenumber of filtersVSAvoidisolation performance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent merges the functions of the BPF and BEF into a coordinated filter system where the BPF handles primary frequency selection and the BEF handles targeted attenuation of specific pass bands. This merging of functions into a two-filter system eliminates the need for separate HPF components while achieving the required isolation performance, thereby reducing overall device complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The BEF is designed to serve multiple purposes: it attenuates the pass band of the BPF while allowing other frequency bands to pass through. This multi-functionality enables a single filter component to perform what would otherwise require multiple specialized filters, reducing the total number of components needed in the system.

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

The proposed multiplexer achieves low loss and high isolation by carefully arranging filters to match attenuation requirements, thereby reducing transmission loss and ensuring efficient signal processing.