Transmitter Noise Rejection via Distributed Filtering Architecture

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Solution Overview

Problem

Traditional radio transmitters face challenges with noise reduction due to the large and costly filters required to handle high power and stringent noise specifications, which restrict gain distribution and pose manufacturing and assembly issues.

Innovation Solution

A transmitter line-up architecture with multiple amplifiers and filters distributed across gain stages, where each filter rejects noise based on the preceding gain stage, allowing for low-cost surface mount filters and improved noise performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a single high-rejection filter is used to reject far out noise in high power transmitters, then noise rejection capability is improved, but filter size and cost increase significantly

Engineering Contradiction:

Improvefar out noise rejectionVSAvoidfilter size

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The patent divides the filtering function into multiple filters distributed across different gain stages rather than using a single filter. The transmitter line-up includes a first filter between stage 1 and stage 2, and a second filter between stage 2 and stage 3, with each filter handling a portion of the noise rejection requirement proportional to the gain preceding it. This segmentation reduces the rejection burden on each individual filter, allowing smaller, more manageable filter sizes.

Inventive Principle:

Principle #1Segmentation

2Object-affected harmful factors

If a single high-rejection filter is used to reject far out noise in high power transmitters, then noise rejection capability is improved, but filter cost increases significantly

Engineering Contradiction:

Improvefar out noise rejectionVSAvoidfilter cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent divides the filtering function into multiple filters distributed across different gain stages rather than using a single filter. The transmitter line-up includes a first filter between stage 1 and stage 2, and a second filter between stage 2 and stage 3, with each filter handling a portion of the noise rejection burden. This segmentation allows the use of lower-cost filters with moderate rejection capabilities rather than requiring one expensive high-rejection filter.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent enables the use of lower-cost surface mount filters in place of expensive, large, difficult-to-manufacture filters. By distributing the filtering function across multiple stages, each filter can be a more affordable component, and surface mount technology facilitates easier assembly and manufacturing.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Power

If gain is increased before a filter to meet power requirements, then transmitter power output is improved, but filter rejection must be increased to maintain noise performance

Engineering Contradiction:

Improvetransmitter power outputVSAvoidnoise rejection requirement

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent segments the gain stages and filters so that each filter only needs to reject noise corresponding to the gain preceding it. Stage 1 has a first filter after it, and stage 2 has a second filter after it. This allows the transmitter to achieve high power output while each filter handles a manageable portion of the noise rejection requirement, avoiding the need for extremely high rejection capability in a single filter.

Inventive Principle:

Principle #1Segmentation

4Object-affected harmful factors

If traditional filtering approaches are used, then noise rejection is achieved, but device complexity and assembly difficulty increase

Engineering Contradiction:

Improvenoise rejectionVSAvoidfilter placement complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent divides the filtering function into multiple discrete filter stages that can be independently placed and managed. The first filter is positioned between stage 1 and stage 2, and the second filter is positioned between stage 2 and stage 3. This segmentation simplifies the overall system design and assembly process compared to implementing a single complex high-rejection filter.

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 approach results in better noise performance and reduced costs by dispersing filtering across gain stages, facilitating easier assembly and cost-effective production of high power devices like mobile radios.

Implementation Method 1

each filter rejects far out noise in the receiver band in accordance with a gain stage preceding that filter

Methodology Applied

Scientific EffectFilter rejection: Filter (electronic)

Data Source

PatentUS7805117B2Method and apparatus for minimizing noise in a transmitter

Publication Date: 2010.09.28 MOTOROLA SOLUTIONS INC

AI summary

A transmitter (200) includes a plurality of amplifier “n” stages (202, 204, 206) providing predetermined gain stages and a plurality of filters (208, 210). Each filter (208, 210) is distributed between each gain stage (202, 204) (204, 206) so as to reject far out noise in accordance with the gain stage preceding that filter.