Frontend Multiplexer Circuit for Carrier Aggregation Leakage Suppression

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Solution Overview

Problem

In carrier aggregation systems, signal leakage between closely spaced receive frequency bands leads to attenuation issues, which existing frontend circuits fail to adequately address, particularly when multiple communication frequency bands are used simultaneously.

Innovation Solution

The implementation of a wide-band filter that passes multiple communication frequency bands, along with selective narrow-band filters for individual bands, reduces signal leakage and eliminates the need for additional narrow-band filters, thereby minimizing size and cost while maintaining effective signal transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If narrow-band filters are used for each communication frequency band, then signal leakage between bands is suppressed, but the device size and cost increase due to requiring multiple filters

Engineering Contradiction:

Improvesignal leakageVSAvoidnumber of filters

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The wide-band filter is designed to handle multiple communication frequency bands (e.g., Band 28A and Band 20) simultaneously, replacing the need for separate narrow-band filters for each band. This multi-functional filter maintains signal integrity across different bands while reducing the total number of filter components required in the frontend circuit.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the filtering functions for multiple frequency bands into a single wide-band filter component. By merging what would traditionally require separate narrow-band filters into one unified filter with a broader frequency response, the system achieves the same signal leakage suppression effect with fewer components, thereby reducing device size and cost.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If multiple narrow-band filters are disposed for different communication frequency bands, then each band can be filtered selectively, but the apparatus size increases

Engineering Contradiction:

Improvesignal transmission qualityVSAvoidapparatus size

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The wide-band filter serves multiple frequency bands (Band 28A, Band 20, and potentially others) with a single component, eliminating the need for multiple separate narrow-band filters. This reduces the physical space required for filter disposal while maintaining reliable signal transmission quality across all supported bands through the filter's broad frequency response characteristics.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Device complexity

If a wide-band filter is used to pass multiple communication frequency bands, then the number of filters is reduced, but signal leakage between closely spaced bands may occur

Engineering Contradiction:

Improvenumber of filtersVSAvoidsignal leakage

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The wide-band filter is designed with specific frequency response parameters that allow it to pass multiple communication bands (such as Band 28A and Band 20) while maintaining adequate rejection of out-of-band signals. The filter's bandwidth and selectivity parameters are optimized to prevent signal leakage between closely spaced bands, achieving this through careful parameter selection rather than using multiple narrower filters.

Inventive Principle:

Principle #35Parameter changes

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

This configuration effectively suppresses signal attenuation due to leakage between closely spaced frequency bands, enabling efficient carrier aggregation across multiple bands without the need for additional filters, thus reducing the size and cost of the apparatus.

Implementation Method 1

a wide-band filter that passes the first communication frequency band and the second communication frequency band

Methodology Applied

Scientific EffectFiltering: Filter (electronic)

Data Source

PatentUS11757482B2Frontend circuit, frontend module, communication apparatus, and multiplexer

Publication Date: 2023.09.12 MURATA MFG CO LTD

AI summary

A frontend circuit includes a wide-band filter, a transmit filter, and switches. The wide-band filter passes both the receive frequency band of a first communication frequency band and that of a second communication frequency band which is close to or overlaps that of the first communication frequency band. The transmit filter passes the transmit frequency band of the first or second communication frequency band. The switches are capable of simultaneously bringing, into conduction, at least two of multiple filters including the wide-band filter and the transmit filter. In carrier aggregation using the receive frequency bands of the first and second communication frequency bands, the switches simultaneously bring the wide-band filter and the transmit filter into conduction. Thus, in carrier aggregation using signals of multiple communication frequencies simultaneously in communication, attenuation of signals due to signal leakage in two receive frequency bands, which are close to each other, is suppressed.