Common Mode Noise Sensor Single Amplification Path

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Solution Overview

Problem

Existing noise sensors face challenges in accurately sensing common mode noise due to phase shifts caused by parallel amplification paths, which affects the accuracy of noise signal detection and requires separate cancellation methods for common mode and differential mode noise.

Innovation Solution

A common mode noise sensor with a single amplification path and a resistor network is designed to suppress differential mode noise in preference to common mode noise, eliminating phase shift issues and reducing the size and cost by avoiding inductive couplings, using operational amplifiers and resistive and capacitive elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Difficulty of detecting and measuring

If parallel amplification paths are used to sense noise signals, then the noise detection capability is enhanced, but phase shifts occur that reduce measurement precision

Engineering Contradiction:

Improvenoise detection capabilityVSAvoidcommon mode noise sensing accuracy

Core Design Contradiction:

Difficulty of detecting and measuringVSMeasurement precision

Solution Approach 1:

The patent merges the sensing of common mode and differential mode noise into a single amplification path. The resistor network is configured to provide different gains for common mode and differential mode signals, allowing both types of noise to be sensed simultaneously without the phase shift problems that occur with parallel amplification paths. This single path approach eliminates the timing differences between separate sensing channels.

Inventive Principle:

Principle #5Merging (Combining)

2Object-affected harmful factors

If passive filters are used to reduce EMI noise, then electromagnetic compatibility is improved, but the device occupies more physical space and consumes more energy

Engineering Contradiction:

ImproveEMI noise reductionVSAvoidPCB space occupation

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The patent replaces the mechanical/passive filter system with an active sensing and cancellation system. Instead of using physical passive filters that occupy PCB space, the invention uses an active filter that senses noise signals and generates cancellation signals electronically. This substitution of mechanical filtering with electronic active filtering reduces the physical footprint on the PCB while maintaining EMI noise reduction effectiveness.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Difficulty of detecting and measuring

If inductive coupling is used to sense noise from power supply, then the sensing capability is achieved, but the device size and cost increase

Engineering Contradiction:

Improvenoise sensing capabilityVSAvoidsensor size and cost

Core Design Contradiction:

Difficulty of detecting and measuringVSDevice complexity

Solution Approach 1:

The patent extracts the noise sensing function from the complex inductive coupling mechanism and implements it through direct resistive coupling with the power supply lines. By removing the inductor component and using only resistors and capacitors in the sensing circuit, the invention achieves noise sensing capability while significantly reducing device size, complexity, and cost. The resistor network directly couples to the power supply to sense both common mode and differential mode noise.

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 solution provides a more accurate representation of common mode noise with a higher ratio of common mode to differential mode noise, enabling effective noise cancellation and reducing system inefficiencies associated with passive filters.

Implementation Method 1

an amplifier stage connected to the first and second terminals and having an output

Methodology Applied

Scientific EffectVoltage amplification:

Implementation Method 2

a resistor network connected to the amplifier stage, the resistor network arranged such that the output of the amplifier stage is configured to provide an output signal in which a differential mode noise in the first and second signals is suppressed

Methodology Applied

Scientific EffectElectrical resistance: Electrical Resistance

Implementation Method 3

The inverting input may be connected to the first terminal via a filter capacitor

Methodology Applied

Scientific EffectCapacitance filtering: Capacitance

Data Source

PatentUS9506969B2Noise sensor

Publication Date: 2016.11.29 NXP BV

AI summary

A common mode noise sensor with a single amplification path is disclosed. The common mode noise sensor includes first and second terminals for receiving respective first and second signals from a power supply, an amplifier stage connected to the first and second terminals and having an output and a resistor network connected to the amplifier stage. The resistor network is arranged such that the output of the amplifier stage is configured to provide an output signal in which a differential mode noise in the first and second signals is suppressed in preference to a common mode noise in the first and second signals.