MOSFET Reference Voltage Circuit for Temperature-Stable Low-Power Output

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Solution Overview

Problem

Existing stabilized voltage generation circuits, such as those using band-gap references, face challenges in maintaining accurate reference voltages over a wide temperature range due to variations in current, resistor matching, and temperature characteristics, leading to deviations of about ±2% and high energy consumption.

Innovation Solution

A reference voltage generation circuit comprising a first voltage generation circuit with positive temperature characteristics and a second voltage generation circuit with negative temperature characteristics, combined through an output adjustment circuit, which uses MOSFETs and variable resistors to generate a stable reference voltage with minimal temperature deviation, achieving a ±0.5% or less deviation over -40°C to 150°C, and reducing current consumption to 1 μA or less.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If band-gap references are used for stabilized voltage generation, then voltage stabilization is achieved, but temperature variation causes ±2% deviation in reference voltage

Engineering Contradiction:

Improvevoltage stabilizationVSAvoidtemperature variation

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent changes the temperature characteristics parameter by using MOSFETs with opposite temperature coefficients (positive and negative) to compensate for each other's variations, achieving stable reference voltage output across temperature ranges without requiring complex temperature compensation circuits

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent combines MOSFETs with different temperature characteristics (positive temperature coefficient and negative temperature coefficient devices) in a composite configuration where their opposing characteristics cancel out temperature variations, creating a temperature-stable reference voltage source

Inventive Principle:

Principle #40Composite materials

2Reliability

If traditional stabilized voltage generation circuits are used, then voltage reference is provided, but current consumption is high

Engineering Contradiction:

Improvevoltage referenceVSAvoidcurrent consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the operating parameters by using MOSFETs in subthreshold or weak inversion regions where devices consume significantly less current while still providing stable voltage references, achieving low-power operation without sacrificing reference voltage stability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs simple MOSFET-based voltage generation circuits that consume minimal current compared to traditional band-gap references, effectively replacing high-power solutions with low-power alternatives that achieve comparable or better performance

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Temperature

If MOSFETs with different gate conductivity types are used, then temperature characteristics vary, but this enables compensation for stability

Engineering Contradiction:

Improvetemperature characteristicsVSAvoidvoltage stability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent applies counterweight by pairing MOSFETs with opposite temperature coefficients (positive and negative) where one device's temperature drift compensates for the other's drift in the opposite direction, achieving temperature-independent reference voltage output

Inventive Principle:

Principle #8Anti-weight (Counterweight)

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

The solution provides a stable reference voltage with reduced temperature variation and low energy consumption, improving the accuracy and efficiency of semiconductor devices across a broad temperature range.

Implementation Method 1

a first MOSFET 121 having a gate of a first conductivity type and a second MOSFET 122 having a gate of a second conductivity type different from the first conductivity type and that is configured to generate a second voltage (ΔNTH) with negative temperature characteristics based on the difference in gate threshold voltage between the first and second MOSFETs

Methodology Applied

Scientific EffectGate threshold voltage difference:

Data Source

PatentUS20240094758A1Stabilized voltage generation circuit and semiconductor device

Publication Date: 2024.03.21 ROHM CO LTD

AI summary

The stabilized voltage generation circuit includes: a first voltage generation circuit configured to generate a first voltage with positive temperature characteristics; and a second voltage generation circuit including a first MOSFET having a gate of a first conductivity type and a second MOSFET having a gate of a second conductivity type different from the first conductivity type and configured to generate a second voltage with negative temperature characteristics based on the difference in gate threshold voltage between the first and second MOSFETs. The output voltage is generated based on the sum voltage of the first and second voltages.