Wake-up Circuit False Positive Reduction via Differential Signal Thresholding

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Solution Overview

Problem

Battery-powered electronic devices face challenges in reducing false wake-up events while minimizing power consumption, leading to inefficient battery life and potential use of larger, more expensive batteries.

Innovation Solution

A wake-up circuit and methodology that produce successive sensor signals in response to physical stimuli, with noise component removal and differential mode detection, prevent communication of wake-up signals when difference values fail to exceed a threshold, ensuring accurate motion detection and reducing false positives.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the device enters sleep mode to save power, then power consumption is reduced, but false wake-up events increase due to noise in sensor signals

Engineering Contradiction:
Improvepower consumptionVSAvoidfalse wake-up events
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The system performs preliminary actions by taking multiple sensor readings and calculating difference values before triggering a wake-up event. This preliminary verification process ensures that noise-induced false positives are filtered out before the device wakes from sleep mode, thereby maintaining reliability while preserving power savings.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by continuously monitoring sensor signals, comparing successive readings, and using the difference values to determine whether a genuine wake-up event has occurred. This feedback mechanism allows the system to distinguish between noise and actual motion, reducing false wake-ups while maintaining low power consumption during sleep mode.

Inventive Principle:
Principle #23Feedback

2Reliability

If the device remains in active mode to avoid false wake-ups, then reliability is improved, but power consumption increases

Engineering Contradiction:
Improvefalse wake-up eventsVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system applies partial action by activating only the necessary verification process (taking multiple readings and calculating differences) when motion is detected, rather than keeping the entire device continuously active. This allows the device to remain in sleep mode with minimal power consumption while still providing sufficient verification to prevent false wake-ups.

Inventive Principle:
Principle #16Partial or excessive action

3Device complexity

If simple motion detection is used to wake the device, then device complexity is reduced, but measurement precision decreases leading to false positives

Engineering Contradiction:
Improvewake-up circuit complexityVSAvoidmotion detection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The system performs preliminary measurements by taking multiple sensor readings and calculating difference values before triggering a wake-up event. This preliminary verification process improves measurement precision without requiring complex hardware, as the additional readings are processed through simple computational logic.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system replaces complex mechanical or hardware-based motion verification with a computational approach using difference value calculations. This substitution maintains low device complexity while significantly improving measurement precision by using software-based filtering of noise-induced false positives.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 significantly reduces false wake-up events, leading to lower power consumption and extended battery life, enabling the use of smaller, less expensive batteries in battery-powered devices.

Implementation Method 1

A wake-up circuit and methodology are provided for detecting and preventing false positive wake-up events in an electronic device in a sleep mode

Methodology Applied
Scientific EffectMotion detection: Accelerometer

Data Source

PatentEP3726340B1Wake-up circuit and methodology for reducing false wake-up events
Publication Date: 2022.08.10 NXP USA INC
  • EP3726340B1 patent drawingFigure 1~3
  • EP3726340B1 patent drawingFigure 4~5
  • EP3726340B1 patent drawingFigure 6

AI summary

A wake-up circuit (22) and method (100) are provided for detecting and preventing false positive wake-up events in an electronic device (24) in a sleep mode (48). Methodology entails producing first, second, and third sensor signals (106, 114, 122) at successive first, second, and third instants in time (40) in response to a physical stimulus detected by a sensor (28) of the wake-up circuit. The first sensor signal (106) is selected to be a reference value (76). A first difference value (78N) is determined between the second sensor signal (114) and the reference value, a second difference value (78N+1) is determined between the third sensor signal and the reference value, and communication of a wake-up signal (52) to the electronic device (24) is prevented when at least one of the first and second difference values fails to exceed a threshold value (118).