Diplexer and Notch Filter Layout for Multi-TDD RF Circuits

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Solution Overview

Problem

Conventional high-frequency circuits are complex and large due to the need for multiple band pass filters and antenna multiplexers to efficiently transmit signals across multiple TDD bands, leading to increased size and complexity.

Innovation Solution

A high-frequency circuit design that includes a diplexer composed of filters for different frequency band groups, notch filters for rejecting unwanted frequencies, and switching circuits to manage signal transmission and reception, without the need for band pass filters between the filters and switching circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple band pass filters and antenna multiplexers are used to transmit signals of multiple TDD bands with low loss, then transmission quality is improved, but circuit complexity and size increase

Engineering Contradiction:

Improvetransmission qualityVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple band pass filters into a single filter structure that handles multiple TDD bands simultaneously. The antenna multiplexer is integrated with the filter system, merging functions that were previously separate into a unified circuit architecture, thereby reducing the number of discrete components while maintaining low-loss transmission across multiple bands

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The designed filter system serves multiple functions: it acts as a band pass filter for multiple TDD bands, an antenna multiplexer for signal routing, and a signal combiner/splitter. This multi-functional design eliminates the need for separate dedicated components for each function, reducing overall circuit complexity while preserving transmission quality

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If multiple band pass filters and antenna multiplexers are used to transmit signals of multiple TDD bands with low loss, then transmission quality is improved, but circuit size increases

Engineering Contradiction:

Improvetransmission qualityVSAvoidcircuit size

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent merges multiple discrete filter components and the antenna multiplexer into a single integrated filter system. This consolidation reduces the physical space required by eliminating redundant housing, mounting areas, and inter-component wiring, while the combined structure maintains the low-loss transmission characteristics across all TDD bands through optimized signal paths

Inventive Principle:

Principle #5Merging (Combining)

3Device complexity

If a simplified circuit configuration is used, then circuit complexity and size are reduced, but transmission quality may deteriorate

Engineering Contradiction:

Improvecircuit complexityVSAvoidtransmission quality

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent optimizes key parameters of the integrated filter system including bandwidth allocation for each TDD band, quality factor (Q-factor) tuning, and impedance matching parameters. By carefully adjusting these parameters, the simplified circuit maintains low insertion loss and high selectivity, ensuring transmission quality is preserved despite the reduced component count

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

The proposed design simplifies and reduces the size of high-frequency circuits while enabling low-loss transmission of signals across multiple TDD bands, improving efficiency and reducing complexity.

Implementation Method 1

a first filter which has a pass band including a first frequency band group which includes a first communication band for time division duplex (TDD) and a second communication band for TDD, and a second filter which has a pass band including a second frequency band group whose frequency does not overlap with a frequency of the first frequency band group

Methodology Applied

Scientific EffectFrequency-selective filtering: Filter (electronic)

Implementation Method 2

a first band rejection filter that is connected with the first filter and whose stop band is a frequency band which is not included in the first communication band; a second band rejection filter that is connected with the first filter and whose stop band is a frequency band which is not included in the second communication band

Methodology Applied

Scientific EffectBand rejection filtering: Filter (electronic)

Data Source

PatentUS12341551B2High-frequency circuit and communication device

Publication Date: 2025.06.24 MURATA MFG CO LTD

AI summary

A high-frequency circuit includes: a diplexer that is composed of a filter which has a pass band including a first frequency band group and a filter which has a pass band including a second frequency band group; a notch filter that is connected with the filter and whose stop band is a frequency band which is not included in a first communication band; a notch filter that is connected with the filter and whose stop band is a frequency band which is not included in a second communication band; and switches that are connected with the notch filters. A band pass filter whose pass band is the first communication band and a band pass filter whose pass band is the second communication band are not connected between the filter and the switches.