Integrated RF Front-End Impedance Tuning for Noise Figure and Gain

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Solution Overview

Problem

Existing transmit-and-receive modules with integrated low-noise and power amplifiers fail to optimize the noise figure and gain balance due to inadequate impedance matching between the low-noise amplifier and the duplexer, leading to suboptimal performance in noise figure and gain.

Innovation Solution

The integration of a duplexer, power amplifier, and low-noise amplifier in a transmit-and-receive module, where the output impedance of the receive filter is set to intersect the line connecting the center points of noise figure and gain circles in a Smith chart, allowing for customized impedance matching that optimizes both noise figure and gain, eliminating the need for additional impedance matching circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If characteristic impedance matching is used between the low-noise amplifier and duplexer, then the module size is reduced through integration, but the noise figure and gain performance deteriorate

Engineering Contradiction:

Improvemodule sizeVSAvoidnoise figure and gain performance

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent applies local quality by setting different impedance values for different parts of the system. Specifically, the receive filter unit is designed with an output impedance that intersects the line connecting the center points of noise figure circles and gain circles in the Smith chart, rather than using uniform characteristic impedance matching. This localized impedance optimization enables simultaneous improvement of noise figure and gain performance while maintaining module integration

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the impedance parameter from standard characteristic impedance to a customized impedance value. The output impedance of the receive filter unit is specifically designed to intersect the optimal performance line in the Smith chart, representing a parameter change that optimizes both noise figure and gain. This parameter modification resolves the contradiction by achieving better performance metrics without increasing module size

Inventive Principle:

Principle #35Parameter changes

2Reliability

If additional impedance matching circuits are added to optimize noise figure and gain, then performance improves, but device complexity and size increase

Engineering Contradiction:

Improvenoise figure and gain performanceVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the impedance matching function into the receive filter unit itself, eliminating the need for separate impedance matching circuits. The receive filter unit is designed with an output impedance that inherently intersects the optimal performance line in the Smith chart, combining filtering and impedance matching functions into a single component. This merging reduces device complexity while maintaining optimized noise figure and gain performance

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If additional impedance matching circuits are added to optimize noise figure and gain, then performance improves, but the module size increases

Engineering Contradiction:

Improvenoise figure and gain performanceVSAvoidmodule size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent combines the impedance matching functionality into the receive filter unit, eliminating the need for separate impedance matching circuits. By designing the receive filter unit with an output impedance that intersects the optimal performance line in the Smith chart, the patent achieves optimized noise figure and gain performance without adding extra components or increasing module size

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The receive filter unit is designed to perform multiple functions simultaneously: signal filtering and impedance matching. By making the receive filter unit universal, it can optimize both noise figure and gain performance through its specially designed output impedance without requiring additional dedicated impedance matching circuits, thus avoiding increases in module size

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10771102B2Transmit-and-receive module and communication device

Publication Date: 2020.09.08 MURATA MFG CO LTD

AI summary

A transmit-and-receive module includes a multiplexer, a power amplifier, and a low-noise amplifier. The multiplexer includes a transmit filter and a receive filter. The power amplifier and the low-noise amplifier are integrated with each other. In a Smith chart, impedance in a receive band of the receive filter seen from a receive terminal intersects a line connecting a center point of noise figure circles and a center point of gain circles. The center point of the noise figure circles represents the impedance at which the noise figure of the low-noise amplifier is minimized. The center point of the gain circles represents the impedance at which the gain of the low-noise amplifier is maximized.