Device and method for capacitive sensing

Solution Overview

Problem

Existing capacitive sensing systems face challenges due to voltage incompatibility between logic circuitry and analog circuits, leading to increased silicon area and costs, particularly with level shifters configured to output negative level-shifted outputs.

Innovation Solution

A processing system incorporating a level shifter that generates both graylevel and capacitive sensing control data outputs, reducing silicon area by controlling both drive and capacitive sensing circuits, thereby addressing voltage incompatibility issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate level shifters are used for drive circuit and capacitive sensing circuit, then voltage compatibility is achieved, but silicon area and manufacturing costs increase

Engineering Contradiction:

Improvevoltage compatibilityVSAvoidsilicon area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent combines two separate level shifter functions into a single level shifter circuit that can generate both the first level-shifted output for the drive circuit and the second level-shifted output for the capacitive sensing circuit. This merging eliminates redundant circuitry and reduces the overall silicon area occupied by level shifting functionality while maintaining voltage compatibility for both circuits.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The level shifter is designed as a universal circuit that performs multiple functions: it generates different voltage levels for both the drive circuit and the capacitive sensing circuit based on control signals. This multi-functional design allows a single circuit to replace what would traditionally require separate dedicated level shifters for each circuit, thereby reducing area and cost.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If separate level shifters are used for drive circuit and capacitive sensing circuit, then voltage compatibility is achieved, but manufacturing costs increase

Engineering Contradiction:

Improvevoltage compatibilityVSAvoidmanufacturing costs

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent combines two separate level shifter functions into a single level shifter circuit that can generate both the first level-shifted output for the drive circuit and the second level-shifted output for the capacitive sensing circuit. This merging eliminates redundant circuitry and reduces the overall silicon area occupied by level shifting functionality while maintaining voltage compatibility for both circuits.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The level shifter is designed as a universal circuit that performs multiple functions: it generates different voltage levels for both the drive circuit and the capacitive sensing circuit based on control signals. This multi-functional design allows a single circuit to replace what would traditionally require separate dedicated level shifters for each circuit, thereby reducing area and cost.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Area of stationary object

If a single level shifter controls both drive and capacitive sensing circuits, then silicon area is reduced, but circuit complexity increases

Engineering Contradiction:

Improvesilicon areaVSAvoidcircuit complexity

Core Design Contradiction:

Area of stationary objectVSDevice complexity

Solution Approach 1:

The level shifter employs dynamic control mechanisms where control signals selectively enable different output functions based on operational mode. The circuit transitions between generating first level-shifted outputs for drive operations and second level-shifted outputs for sensing operations, allowing a single circuit to adapt its behavior dynamically rather than requiring static dedicated circuits for each function.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The level shifter operates in periodic cycles, alternating between drive mode and sensing mode operations. During drive periods, it generates voltage levels appropriate for the drive circuit; during sensing periods, it generates voltage levels appropriate for the capacitive sensing circuit. This time-division multiplexing approach manages complexity by sequencing operations rather than handling all functions simultaneously.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS11556212B2Device and method for capacitive sensing

Publication Date: 2023.01.17 SYNAPTICS INC

AI summary

A processing system includes a level shifter, a drive circuit, and a capacitive sensing circuit. The level shifter is configured to generate a first level-shifted output corresponding to a graylevel value and a second level-shifted output corresponding to capacitive sensing control data. The drive circuit is configured to generate an output voltage based at least in part on the first level-shifted output. The capacitive sensing circuit is configured to receive a resulting signal from a sensor electrode and generate, based at least in part on the second level-shifted output, a capacitive sensing output corresponding to the resulting signal.