Multiband Front-End Circuit Using a Single Balanced RF Filter

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Solution Overview

Problem

The existing front-end circuits for communication devices require multiple filters for each communication band, leading to increased size and complexity as the number of bands increases, making it difficult to achieve a compact design for multiband and multimode compatibility with low loss.

Innovation Solution

A front-end circuit design that includes a single filter capable of converting unbalanced radio frequency signals into balanced signals, with two low-noise amplifiers connected to the filter's output terminals, allowing simultaneous transfer of radio frequency signals across multiple communication bands with reduced unnecessary signal input and distortion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple filters are disposed for each communication band, then radio frequency signals can be transferred in multiple bands, but the front-end circuit grows in size

Engineering Contradiction:

Improvemultiband compatibilityVSAvoidfront-end circuit size

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent merges multiple filter functions into a single filter by implementing multiple passbands within one filter structure. This single filter simultaneously handles multiple communication bands (e.g., LTE and 5G NR bands) that would traditionally require separate filters, thereby reducing the overall circuit size while maintaining multiband compatibility

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single filter is designed with multi-functionality to serve multiple communication bands simultaneously. By incorporating multiple passbands with different frequency ranges into one filter, it replaces multiple specialized filters, achieving both size reduction and maintained adaptability across different bands

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If multiple filters are used for each path, then signal filtering is effective, but the number of components increases

Engineering Contradiction:

Improvesignal filtering performanceVSAvoidnumber of components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Multiple filtering functions are combined into a single filter component that provides multiple passbands. This merging maintains effective signal filtering for different bands while reducing the component count from multiple filters to just one, thereby simplifying the device structure

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single filter is segmented into multiple functional passbands, each handling different frequency ranges. This segmentation allows the filter to perform multiple filtering operations simultaneously within one component, maintaining reliability while reducing complexity

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11177780B2Front-end circuit and communication device

Publication Date: 2021.11.16 MURATA MFG CO LTD

AI summary

A front-end circuit includes: a filter that converts an unbalanced radio frequency signal inputted to an input terminal into two balanced radio frequency signals, and outputs one of the two balanced radio frequency signals from an output terminal and the other of the two balanced radio frequency signals from another output terminal; a low-noise amplifier connected to the output terminal; and a low-noise amplifier connected to the other output terminal.