Tunable Bandgap Voltage Reference Circuit for Temperature Adaptation

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Solution Overview

Problem

Existing voltage regulation systems in integrated circuits, such as FPGAs, face challenges in maintaining transistor performance and gate oxide durability across varying temperatures, with performance degrading at lower temperatures and susceptibility to gate oxide breakdown at higher temperatures.

Innovation Solution

A voltage supply circuit that generates a composite bandgap reference voltage with adjustable temperature characteristics, using a single bandgap reference voltage circuit and a select circuit to dynamically switch between different voltage versus temperature relationships, allowing for optimal performance and durability across temperature ranges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a fixed bandgap reference voltage is used, then the circuit is simple, but the transistor performance degrades at low temperatures and gate oxide durability decreases at high temperatures

Engineering Contradiction:

Improvecircuit complexityVSAvoidtransistor performance and gate oxide durability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent divides the single bandgap reference voltage into multiple selectable bandgap voltages with different temperature coefficients. The bandgap reference circuit is segmented into multiple output channels, each providing a voltage with specific temperature characteristics, allowing selection based on operating temperature conditions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic selection of bandgap reference voltage based on temperature conditions. A temperature sensor detects the operating temperature and controls a switch to select the appropriate bandgap voltage, making the system adaptive rather than static. This dynamic adjustment optimizes transistor performance across different temperature ranges.

Inventive Principle:

Principle #15Dynamics

2Power

If the bandgap reference voltage is increased to maintain drive strength at low temperatures, then transistor drive strength is improved, but gate oxide breakdown susceptibility increases at high temperatures

Engineering Contradiction:

Improvetransistor drive strengthVSAvoidgate oxide breakdown susceptibility

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent applies different voltage characteristics to different temperature conditions. At low temperatures, a bandgap voltage with higher temperature coefficient is selected to maintain drive strength. At high temperatures, a bandgap voltage with lower temperature coefficient is selected to reduce gate oxide stress. Each temperature range receives the locally optimal voltage characteristic.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the temperature coefficient parameter of the bandgap reference voltage based on operating conditions. By selecting from multiple bandgap voltages with different temperature coefficients, the system adjusts this critical parameter to optimize both drive strength and reliability across the temperature range.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If multiple bandgap reference voltage circuits are used to provide different voltage versus temperature relationships, then temperature adaptability is improved, but device complexity increases

Engineering Contradiction:

Improvetemperature adaptabilityVSAvoidcircuit complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent makes a single bandgap reference circuit multi-functional by extracting multiple bandgap voltages from one reference source. This single circuit serves multiple purposes by providing different voltage outputs with different temperature characteristics, eliminating the need for multiple separate bandgap reference circuits.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent introduces a switch as an intermediary element that selects between different bandgap voltages based on temperature conditions. This mediator component enables flexible switching between different voltage characteristics without requiring multiple independent voltage generation circuits, thus reducing overall complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS7307468B1Bandgap system with tunable temperature coefficient of the output voltage

Publication Date: 2007.12.11 XILINX INC

AI summary

A voltage supply circuit for generating a composite bandgap reference voltage includes a single bandgap reference voltage circuit and a select circuit. The bandgap reference circuit has a first output to generate a first bandgap voltage having a first temperature coefficient and has a second output to generate a second bandgap voltage having a second temperature coefficient that is different from the first temperature coefficient. The select circuit has a first input to receive the first bandgap voltage, a second input to receive the second bandgap voltage, and an output to selectively provide either the first bandgap voltage or the second bandgap voltage as the composite bandgap reference voltage.