Fingerprint Sensor IO-Voltage Sensing Via Digital Input Pads

Solution Overview

Problem

Existing fingerprint sensors require dedicated bond pads for IO supply voltage determination, imposing design constraints and space limitations, especially in compact devices.

Innovation Solution

A fingerprint sensor with IO-voltage determining circuitry that senses the voltage level of digital signals to determine the nominal voltage level for data encoding, eliminating the need for dedicated pads and simplifying the design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If dedicated bond pads are used for IO supply voltage determination, then voltage level control is achieved, but device area increases and design complexity increases

Engineering Contradiction:

Improvevoltage level controlVSAvoiddevice area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent merges the IO supply voltage determination function with existing digital signal input pads. The IO-voltage determining circuitry uses the voltage level of incoming digital signals (such as reset or data signals) to automatically determine the nominal voltage level, eliminating the need for separate dedicated bond pads for voltage determination. This combines multiple functions into existing structures, reducing device area while maintaining voltage control reliability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The input pads are given dual functionality: they serve both as digital signal inputs and as sources for IO supply voltage determination. The IO-voltage determining circuitry samples the voltage level of any digital signal received on these pads to infer the appropriate IO supply voltage. This multi-functional approach eliminates dedicated voltage determination pads and reduces overall device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If dedicated bond pads are used for IO supply voltage determination, then voltage level control is achieved, but design complexity increases

Engineering Contradiction:

Improvevoltage level controlVSAvoiddesign complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the IO supply voltage determination function with existing digital signal input pads. The IO-voltage determining circuitry uses the voltage level of incoming digital signals (such as reset or data signals) to automatically determine the nominal voltage level, eliminating the need for separate dedicated bond pads for voltage determination. This combines multiple functions into existing structures, reducing device area while maintaining voltage control reliability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The system uses the incoming digital signals themselves to determine the IO supply voltage level. Rather than requiring external voltage determination circuits or dedicated pads, the fingerprint sensor automatically samples the voltage level of received digital signals and uses this information to configure its internal voltage levels. This self-service approach reduces design complexity by eliminating the need for separate voltage determination mechanisms.

Inventive Principle:

Principle #25Self-service

3Reliability

If IO supply voltage is determined through dedicated pads, then voltage accuracy is maintained, but space for bond pads is reduced

Engineering Contradiction:

Improvevoltage accuracyVSAvoidspace for bond pads

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent merges the IO supply voltage determination function with existing digital signal input pads. The IO-voltage determining circuitry uses the voltage level of incoming digital signals (such as reset or data signals) to automatically determine the nominal voltage level, eliminating the need for separate dedicated bond pads for voltage determination. This combines multiple functions into existing structures, reducing device area while maintaining voltage control reliability.

Inventive Principle:

Principle #5Merging (Combining)

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

Enables a more compact and efficient fingerprint sensor design by eliminating the need for dedicated IO-voltage pads, reducing misinterpretation risks and potential damage to external circuitry.

Implementation Method 1

IO-voltage determining circuitry coupled to the first input pad and configured to sense a voltage level of the first digital signal, and to determine, based on the sensed voltage level of the first digital signal, a nominal voltage level to use for the digital data signal

Methodology Applied

Scientific EffectVoltage sensing: Ohm's Law

Data Source

PatentUS12462597B2Fingerprint sensor with IO-voltage determining circuitry

Publication Date: 2025.11.04 FINGERPRINT CARDS ANACATUM IP AB

AI summary

A fingerprint sensor, comprising fingerprint sensing circuitry configured to sense a fingerprint of a finger, and to provide a representation of the fingerprint; a sensor interface coupled to the fingerprint sensing circuitry, and comprising at least a first input pad for input to the fingerprint sensor of at least a first digital signal, and at least one output pad for output from the fingerprint sensor of a digital data signal encoding the representation of the fingerprint; and IO-voltage determining circuitry coupled to the first input pad and configured to sense a voltage level of the first digital signal, and to determine, based on the sensed voltage level of the first digital signal, a nominal voltage level to use for the digital data signal encoding the representation of the fingerprint.