In-Phase Quadrature Interference Detection for Proximity Sensors

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Solution Overview

Problem

Proximity sensor devices face challenges in accurately determining interference at specific frequencies, which affects their ability to mitigate interference and provide reliable user input detection, as existing solutions often rely solely on in-phase component analysis, neglecting the quadrature component that may contain majority of the interference power.

Innovation Solution

The implementation of an input device with both in-phase and quadrature interference detection blocks, utilizing an analog mixer, ADC, and decimation filters to determine both components of interference at a specific frequency, allowing for concurrent estimation and mitigation of interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If only in-phase component analysis is used for interference detection, then the device complexity is reduced, but the measurement precision of interference is insufficient because the quadrature component containing majority of interference power is neglected

Engineering Contradiction:

Improveinterference detection precisionVSAvoiddetection block complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The interference detection function is segmented into two independent detection blocks: an in-phase interference detection block and a quadrature interference detection block. Each block processes a specific component (in-phase or quadrature) separately, allowing the system to capture complete interference information without requiring a single overly complex detection mechanism. This segmentation enables precise measurement of both components while maintaining manageable complexity in each individual block.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system transitions from one-dimensional in-phase component analysis to two-dimensional analysis by adding the quadrature component dimension. The in-phase and quadrature components represent orthogonal dimensions of the interference signal, and by detecting both dimensions simultaneously through separate detection blocks, the system achieves complete interference characterization that cannot be obtained through in-phase analysis alone.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If both in-phase and quadrature interference detection blocks are implemented, then the reliability of user input detection is improved by considering both components, but the device complexity increases

Engineering Contradiction:

Improveuser input detection reliabilityVSAvoidinterference detection system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The reliable detection of user input is achieved by segmenting the interference cancellation process into two specialized blocks: one for in-phase component processing and another for quadrature component processing. Each block is optimized for its specific function, and their combined outputs provide comprehensive interference mitigation. This segmentation allows the system to reliably distinguish user input from interference by considering both orthogonal components independently.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The in-phase and quadrature detection blocks act as intermediaries that separately process different components of the interference signal. By introducing these intermediary detection blocks, the system can independently analyze and mitigate interference from each component before combining the results, thereby improving the overall reliability of user input detection without requiring a single monolithic complex detection system.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enables accurate determination and mitigation of interference, improving the reliability of user input detection by considering both in-phase and quadrature components, thereby enhancing the performance of proximity sensor devices.

Implementation Method 1

an analog mixer configured to mix a resulting signal associated with a capacitive sensor electrode with a local oscillator (LO) signal

Methodology Applied

Scientific EffectMixing:

Implementation Method 2

a first decimation filter configured to determine an in-phase component of an interference at a frequency of the LO signal based, at least in part, on the digital signal

Methodology Applied

Scientific EffectDecimation filtering: Filter (electronic)

Implementation Method 3

a first quadrature interference detection block comprising: a second decimation filter configured to determine a quadrature component of the interference at the frequency

Methodology Applied

Scientific EffectQuadrature filtering: Filter (electronic)

Data Source

PatentUS10203809B2Interference detection

Publication Date: 2019.02.12 SYNAPTICS INC

AI summary

An input device including: a first in-phase touch sensing block including: an analog mixer configured to mix a resulting signal associated with a capacitive sensor electrode with a local oscillator (LO) signal; an analog to digital converter (ADC) configured to convert an output of the analog mixer into a digital signal; and a first decimation filter configured to determine an in-phase component of an interference at a frequency of the LO signal based, at least in part, on the digital signal; and a first quadrature interference detection block including: a second decimation filter configured to determine a quadrature component of the interference at the frequency.