Integrated Current Sensor Calibration for Accurate PCB-Saving Sensing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional current sensing systems in wireless power systems face challenges with increased board space and PCB layout complexity due to the use of external sense resistors, and require accurate calibration to compensate for variations in integrated sense resistors caused by temperature, manufacturing, and aging.

Innovation Solution

Integration of the sense resistor within the IC alongside an amplifier, along with an external capacitor, and implementation of calibration schemes to determine the transimpedance gain, using a reference current and mirrored current to compensate for variations, thereby reducing PCB component count and improving system integration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If external sense resistors are used in current sensing systems, then measurement precision is improved, but device complexity and board space increase

Engineering Contradiction:

Improvecurrent sensing accuracyVSAvoidPCB layout complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent integrates the sense resistor directly into the IC package alongside the amplifier circuit, eliminating the need for external sense resistors and reducing PCB component count while maintaining current sensing functionality

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated circuit performs multiple functions including current sensing, amplification, and filtering within a single package, with the sense resistor serving both as a measurement element and as part of the overall circuit integration strategy

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If external sense resistors are used in current sensing systems, then measurement precision is improved, but device complexity and board space increase

Engineering Contradiction:

Improvecurrent sensing accuracyVSAvoidboard space

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The sense resistor is merged with the amplifier IC in a single integrated package, eliminating the need for separate external components and reducing the overall board space required for current sensing implementation

Inventive Principle:

Principle #5Merging (Combining)

3Device complexity

If integrated sense resistors are used, then device complexity is reduced, but measurement precision deteriorates due to manufacturing and temperature variations

Engineering Contradiction:

ImprovePCB component countVSAvoidcurrent sensing accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements a calibration mechanism where the system measures the actual resistance value of the integrated sense resistor and uses this feedback information to compensate for manufacturing variations and temperature effects, maintaining measurement precision despite using integrated components

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts measurement parameters based on the calibrated resistance value, changing the gain or scaling factors to account for variations in the integrated sense resistor characteristics across different operating conditions

Inventive Principle:

Principle #35Parameter changes

4Device complexity

If integrated sense resistors are used, then device complexity is reduced, but reliability deteriorates due to temperature and aging variations

Engineering Contradiction:

ImprovePCB component countVSAvoidresistor stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent performs calibration measurements during manufacturing or initial operation to establish baseline resistance values before the integrated sense resistor is subjected to temperature and aging effects, allowing for compensation of future drift

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors and compensates for resistance variations caused by temperature and aging through feedback mechanisms, adjusting measurement parameters to maintain reliability over the device lifetime

Inventive Principle:

Principle #23Feedback

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

Achieves accurate current sensing with reduced PCB complexity and compensation for resistor variations, ensuring efficient and reliable operation of wireless power systems.

Implementation Method 1

measuring a voltage drop across the sense resistor

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Implementation Method 2

copying the reference current to generate a mirrored current

Methodology Applied

Scientific EffectCurrent Mirroring:

Data Source

PatentUS20250383419A1Calibration of integrated current sensor

Publication Date: 2025.12.18 RENESAS ELECTRONICS AMERICA INC

AI summary

Systems and methods for implementing calibration of an integrated current sensor are described. A reference current can be applied to a sense resistor in a current sensing circuit. The reference current can be copied to generate a mirrored current. A magnitude of the reference current can be determined based on the mirrored current. A voltage drop across the sense resistor can be measured. A gain of the current sensing circuit can be determined based on the determined magnitude of the reference current and the measured voltage drop.