Reference Voltage Generator Using NMOS Threshold Variation

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Solution Overview

Problem

As semiconductor devices integrate and become more complex, temperature changes lead to performance degradation due to variations in current flow, affecting the stability of reference voltages generated in semiconductor devices and systems.

Innovation Solution

A reference voltage generator is designed with a mirroring circuit and voltage generation circuits that produce constant sub-voltages and voltage differences, utilizing NMOS transistors with different threshold voltages to maintain a constant reference voltage output despite temperature changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If semiconductor devices are integrated and operations become more complicated, then functionality and complexity increase, but temperature changes cause current flow variations that degrade performance and reference voltage stability

Engineering Contradiction:

ImprovefunctionalityVSAvoidreference voltage stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent changes the threshold voltage parameter of transistors by using different transistor types (PMOS vs NMOS) with inherently different threshold voltages. This parameter difference is exploited to create a temperature-compensated reference voltage that remains stable despite temperature variations caused by increased device integration and complexity.

Inventive Principle:

Principle #35Parameter changes

2Temperature

If temperature increases, then operational complexity increases, but current flow through elements is reduced, resulting in reduced operation speed and performance degradation

Engineering Contradiction:

Improveoperational temperatureVSAvoidoperation speed

Core Design Contradiction:

TemperatureVSProductivity

Solution Approach 1:

The patent implements a feedback mechanism where the reference voltage generator continuously monitors and compensates for temperature-induced current variations. By using the different threshold voltages of PMOS and NMOS transistors, the circuit automatically adjusts to maintain constant current flow and operation speed across varying temperatures.

Inventive Principle:

Principle #23Feedback

3Device complexity

If conventional reference voltage generators are used, then device simplicity is maintained, but reference voltage varies with temperature changes

Engineering Contradiction:

Improvecircuit structureVSAvoidreference voltage constancy

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

The patent uses a composite approach by combining PMOS and NMOS transistors with different threshold voltage characteristics into a single reference voltage generator circuit. This composite structure leverages the complementary properties of the two transistor types to achieve temperature-independent reference voltage output.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS10168723B2Reference voltage generator being tolerant of temperature variation

Publication Date: 2019.01.01 SK HYNIX INC

AI summary

A reference voltage generator includes a mirroring circuit generating a first sub-voltage and a second sub-voltage that are constant, a first voltage generator including a first switch generating a first voltage based on the first sub-voltage, and a second voltage generator including a second switch generating a second voltage that is lower than the first voltage based on the second sub-voltage, wherein the second switch has a threshold voltage that is lower than the first switch to keep a voltage difference between the first voltage and the second voltage as a first reference voltage.