RF Switch and Filter Layout for Multiband Simultaneous Transmission

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Solution Overview

Problem

Radio-frequency circuits used for multiband communication often experience deterioration in performance when transmitting signals in multiple frequency bands simultaneously.

Innovation Solution

A radio-frequency circuit design incorporating specific switch circuits and filters, including a low-pass and high-pass filter configuration, to manage signal paths and suppress harmonic interference, thereby reducing insertion loss and enhancing isolation between frequency bands.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a multiplexer with multiple filters is used to handle multiple frequency bands, then the circuit can support multiband communication, but communication performance deteriorates when simultaneously transmitting signals in multiple frequency bands

Engineering Contradiction:

Improvemultiband communication capabilityVSAvoidcommunication performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The circuit is divided into separate signal paths: a first signal path for fundamental frequency signals and a second signal path for harmonic frequency signals. Each path has dedicated filters and amplifiers, allowing independent optimization and avoiding the performance deterioration that occurs when multiple frequency bands are simultaneously transmitted through a single multiplexer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A harmonic frequency component extraction circuit acts as an intermediary to separate harmonic components from fundamental frequency signals. This extraction circuit includes a bandpass filter that selectively passes harmonic frequencies, enabling the system to process different frequency components through appropriate paths without interference.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-generated harmful factors

If filters are added to suppress harmonic frequencies, then harmonic interference is reduced, but insertion loss increases

Engineering Contradiction:

Improveharmonic interferenceVSAvoidinsertion loss

Core Design Contradiction:

Object-generated harmful factorsVSLoss of energy

Solution Approach 1:

Different signal paths are assigned different filter characteristics tailored to their specific functions. The first signal path uses filters optimized for fundamental frequency signals, while the second signal path uses filters optimized for harmonic frequencies. This local optimization ensures that each path achieves the necessary filtering performance without excessive insertion loss for its intended signal type.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of treating harmonic frequencies as purely harmful signals to be eliminated, the invention extracts and utilizes them through a dedicated second signal path with appropriate filters and amplifiers. This converts the harmful harmonic components into useful signal carriers for additional communication channels, thereby reducing the need for aggressive harmonic suppression in the first path.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Object-generated harmful factors

If isolation between frequency bands is enhanced, then interference between bands is reduced, but device complexity increases

Engineering Contradiction:

Improveinterference between frequency bandsVSAvoidcircuit structure

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The harmful harmonic frequency components are extracted and removed from the main signal path using a dedicated extraction circuit. This prevents harmonic interference from affecting other frequency bands while keeping the main transmission path simple and efficient.

Inventive Principle:

Principle #2Taking out (Extraction)

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 effectively suppresses communication performance deterioration by minimizing harmonic interference and insertion loss, enabling efficient simultaneous transmission across multiple frequency bands.

Implementation Method 1

a second filter that has the first frequency band as at least a part of a passband and has a second frequency band including a second frequency that is n times (n is a natural number greater than or equal to two) a first frequency in the first frequency band as a stop band

Methodology Applied

Scientific EffectFrequency filtering: Filter (electronic)

Implementation Method 2

a third filter having a third frequency band including the second frequency as a passband

Methodology Applied

Scientific EffectFrequency filtering: Filter (electronic)

Data Source

PatentUS12562759B2Radio-frequency circuit and communication device

Publication Date: 2026.02.24 MURATA MFG CO LTD

AI summary

A radio-frequency circuit includes an antenna connection terminal, switch circuits, a duplexer, a low-pass filter, and a high-pass filter. The switch circuit includes a port connected to the antenna connection terminal and ports. The switch circuit includes a single transmission port connected to the port, a simultaneous transmission port connected to ports. The duplexer is connected to the port. The low-pass filter is disposed on a signal path connecting the port and the simultaneous transmission port. The high-pass filter is connected to the port. No filter is disposed on a signal path connecting the port and the single transmission port.