Low-Voltage Current Reference Circuit for Temperature Stability

Solution Overview

Problem

Existing low-voltage current references are temperature-sensitive due to the variances caused by bandgap circuits, which occupy significant circuit space and consume considerable power, necessitating a solution for a temperature-insensitive current source with reduced power and circuit area consumption.

Innovation Solution

A low-voltage current reference design comprising a single low voltage bandgap, a start circuit, and a current summer, which generates a constant current reference by combining proportional to absolute temperature (PTAT) and complementary to absolute temperature (CTAT) currents, eliminating the need for separate PTAT and CTAT bandgaps and start circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If separate PTAT bandgap and CTAT bandgap circuits are used to generate temperature-insensitive current, then temperature stability is improved, but circuit area and power consumption increase

Engineering Contradiction:

Improvetemperature stabilityVSAvoidcircuit area

Core Design Contradiction:

Stability of the object's compositionVSArea of stationary object

Solution Approach 1:

The patent combines the PTAT and CTAT bandgap circuits into a single integrated structure where both current references are generated within one bandgap circuit. The current summer then combines these currents in appropriate ratios to produce a temperature-insensitive output current, eliminating the need for separate dedicated PTAT and CTAT bandgap circuits and their associated start circuits.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single bandgap circuit performs multiple functions: it generates both the PTAT current reference and the CTAT current reference simultaneously. Additionally, a single start circuit is designed to initialize both bandgap circuits, making the start circuit multi-functional and reducing overall circuit complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Stability of the object's composition

If separate PTAT bandgap and CTAT bandgap circuits are used to generate temperature-insensitive current, then temperature stability is improved, but power consumption increases

Engineering Contradiction:

Improvetemperature stabilityVSAvoidpower consumption

Core Design Contradiction:

Stability of the object's compositionVSUse of energy by stationary object

Solution Approach 1:

The patent combines the PTAT and CTAT bandgap circuits into a single integrated structure where both current references are generated within one bandgap circuit. The current summer then combines these currents in appropriate ratios to produce a temperature-insensitive output current, eliminating the need for separate dedicated PTAT and CTAT bandgap circuits and their associated start circuits.

Inventive Principle:

Principle #5Merging (Combining)

3Stability of the object's composition

If multiple bandgap circuits and start circuits are used, then temperature-insensitive current reference is achieved, but device complexity increases

Engineering Contradiction:

Improvetemperature insensitivityVSAvoidcircuit complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent combines the PTAT and CTAT bandgap circuits into a single integrated structure where both current references are generated within one bandgap circuit. The current summer then combines these currents in appropriate ratios to produce a temperature-insensitive output current, eliminating the need for separate dedicated PTAT and CTAT bandgap circuits and their associated start circuits.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single bandgap circuit performs multiple functions: it generates both the PTAT current reference and the CTAT current reference simultaneously. Additionally, a single start circuit is designed to initialize both bandgap circuits, making the start circuit multi-functional and reducing overall circuit complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS7863883B2Low-voltage current reference and method thereof

Publication Date: 2011.01.04 NAN YA TECH

AI summary

A low-voltage current reference providing a current being substantially constant with temperature includes a low voltage bandgap, a start circuit coupled to the low voltage bandgap, and a current summer coupled to the low voltage bandgap and to the start circuit. The low voltage bandgap is for providing a constant voltage reference, and the start circuit is for starting the low voltage bandgap from a non-start mode and for providing a proportional to absolute temperature (PTAT) current reference. The current summer is for providing a constant current reference according to the constant voltage reference and the PTAT current reference.