Voltage-to-Current Converter Without Current Mirror Precision Loss

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Solution Overview

Problem

Utility electricity meters often have unknown accuracy, leading to premature replacement of accurate meters and potential continued operation of inaccurate ones, due to the lack of effective monitoring systems that can continuously assess their accuracy without interrupting measurement processes.

Innovation Solution

A voltage-to-current converter system that generates a current based on input voltage and uses it both as output current and as a current source within the system, reducing the need for high-performance current mirror circuits, thereby improving precision, accuracy, and reducing cost and complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional current mirror circuits are used in voltage-to-current converter systems, then the system can operate continuously, but the precision and accuracy are compromised due to the limitations of current mirror performance

Engineering Contradiction:
Improvemeter accuracyVSAvoidcurrent mirror circuit complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the problematic current mirror circuit from the voltage-to-current converter system and replaces it with an operational amplifier-based circuit. This removal of the current mirror eliminates the source of precision errors while maintaining the continuous operation capability, directly resolving the contradiction between measurement precision and device complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the fundamental operating parameters of the voltage-to-current converter by using an operational amplifier with virtual ground concept instead of transistor-based current mirrors. This parameter change enables high-precision current generation through feedback control, achieving both high accuracy and continuous operation without the limitations of current mirror circuits.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If high-performance current mirror circuits are implemented to improve precision, then measurement accuracy improves, but system cost and complexity increase

Engineering Contradiction:
Improvecurrent conversion accuracyVSAvoidsystem cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive, complex current mirror circuits with a more economical operational amplifier-based solution. The operational amplifier circuit achieves superior precision at lower cost, making the system more manufacturable and economically viable while eliminating the need for high-performance, costly current mirror components.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent substitutes the transistor-based current mirror mechanism with an operational amplifier-based voltage-controlled current source. This substitution uses feedback control and virtual ground concepts to achieve precise current generation without relying on the physical limitations of current mirror transistors, reducing both cost and complexity.

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

Data Source

PatentEP3621200B1Voltage-to-current converter
Publication Date: 2022.01.26 ANALOG DEVICES INT UNLTD CO
  • EP3621200B1 patent drawingFigure 1
  • EP3621200B1 patent drawingFigure 2
  • EP3621200B1 patent drawingFigure 3

AI summary

The present disclosure relates to a voltage-to-current converter. The voltage-to-current converter is configured to generate a current based on an input voltage and for part of the time use the generated current as the output current of the voltage-to-current converter, and for part of the time use the generated current as a current source for the operation of the voltage-to-current converter. This arrangement may reduce the need for high performance current mirror circuits within the voltage-to-current converter, thereby reducing the cost and complexity of the voltage-to-current converter and improving precision and accuracy.