RF Module LNA Filter Placement for Noise Factor

Solution Overview

Problem

Existing radio frequency modules with filters placed before low noise amplifiers can suppress signal distortion but may not satisfy the required noise factor performance.

Innovation Solution

A radio frequency module design with a low noise amplifier and a filter placed after the amplifier, where the filter has a pass band including the frequency of the radio frequency reception signal, allowing for improved noise factor reduction by distributing the filter function post-amplification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a filter is arranged before the low noise amplifier to suppress signal distortion, then signal distortion is reduced, but the noise factor performance cannot be satisfied

Engineering Contradiction:

Improvesignal distortionVSAvoidnoise factor

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent inverts the conventional filter placement by positioning the filter after the low noise amplifier instead of before it. This reversal allows the LNA to first amplify the weak received signal with minimal noise addition, and then the filter removes unwanted frequency components. This inversion resolves the contradiction by achieving both signal distortion suppression and acceptable noise factor performance.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent segments the signal processing functions into distinct stages: first amplification by the LNA, then filtering by the frequency selection circuit. This segmentation allows each component to perform its function optimally without compromising the other, enabling the system to achieve both low noise factor and effective signal distortion suppression.

Inventive Principle:

Principle #1Segmentation

2Object-affected harmful factors

If a filter is placed before the low noise amplifier to ensure attenuation near the pass band, then signal distortion in the LNA is reduced, but the required noise factor performance cannot be satisfied

Engineering Contradiction:

Improvesignal distortionVSAvoidnoise factor

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent inverts the conventional filter placement by positioning the filter after the low noise amplifier instead of before it. This reversal allows the LNA to first amplify the weak received signal with minimal noise addition, and then the filter removes unwanted frequency components. This inversion resolves the contradiction by achieving both signal distortion suppression and acceptable noise factor performance.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent segments the signal processing functions into distinct stages: first amplification by the LNA, then filtering by the frequency selection circuit. This segmentation allows each component to perform its function optimally without compromising the other, enabling the system to achieve both low noise factor and effective signal distortion suppression.

Inventive Principle:

Principle #1Segmentation

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 reduces the noise factor more effectively than traditional designs with centralized filter functions before the low noise amplifier, enhancing the overall noise performance of the reception amplification circuit.

Implementation Method 1

a low noise amplifier configured to amplify a radio frequency reception signal input from the signal input terminal

Methodology Applied

Scientific EffectLow noise amplification:

Implementation Method 2

a first filter connected between an output terminal of the low noise amplifier and the signal output terminal and having a pass band including a frequency of the radio frequency reception signal

Methodology Applied

Scientific EffectFrequency filtering: Filter (electronic)

Data Source

PatentUS11956003B2Radio frequency module and communication device

Publication Date: 2024.04.09 MURATA MFG CO LTD

AI summary

A radio frequency module includes a signal input terminal, a signal output terminal, a low noise amplifier configured to amplify a radio frequency reception signal input from the signal input terminal, and a first filter connected between an output terminal of the low noise amplifier and the signal output terminal and having a pass band including a frequency of the radio frequency reception signal.