Differential PTAT Current Circuit for Temperature Compensation

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Solution Overview

Problem

Temperature fluctuations affect the reliability of semiconductor circuits by altering read current flow, leading to decreased read tolerance and inaccurate data retrieval, and constant current circuits experience varying temperature coefficients that impact oscillator periods.

Innovation Solution

A temperature compensation circuit utilizing two PTAT current sources with different emitter area ratios and a differential circuit to generate a high-precision, temperature-compensated current by adjusting the current magnitudes to achieve a temperature coefficient close to zero, ensuring stability across varying temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a constant current circuit is used to avoid voltage dependence, then voltage independence is improved, but temperature coefficient variation affects oscillator period

Engineering Contradiction:

Improvevoltage independenceVSAvoidtemperature coefficient

Core Design Contradiction:

Stability of the object's compositionVSTemperature

Solution Approach 1:

The patent changes the temperature coefficient parameter by using two PTAT current sources with different emitter area ratios (first and second emitter area ratios). By adjusting these ratios and the proportionality coefficients (first and second proportionality coefficients), the circuit achieves a differential current with minimized temperature dependence, thus resolving the temperature coefficient issue while maintaining voltage independence.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent combines two different PTAT current sources with distinct emitter area ratios to create a composite current system. This composite approach allows the temperature coefficients to complement each other, achieving a net temperature-compensated current that maintains stability across temperature variations.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If read current flow decreases due to temperature changes, then circuit operation is maintained, but read tolerance decreases and data retrieval accuracy deteriorates

Engineering Contradiction:

Improvecircuit operationVSAvoidread tolerance

Core Design Contradiction:

Stability of the object's compositionVSMeasurement precision

Solution Approach 1:

The patent converts the harmful effect of temperature-induced current variation into a beneficial temperature-compensated current. By deliberately designing two PTAT current sources with different emitter area ratios, the circuit generates a differential current that actively compensates for temperature effects, thereby maintaining both circuit operation and read tolerance across temperature variations.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Temperature

If a single PTAT current source is used, then temperature dependence is reduced, but precision is insufficient

Engineering Contradiction:

Improvetemperature dependenceVSAvoidcurrent precision

Core Design Contradiction:

TemperatureVSMeasurement precision

Solution Approach 1:

The patent segments the temperature compensation function into two separate PTAT current sources with different emitter area ratios. Each current source handles a portion of the temperature compensation task, and their differential combination achieves higher precision than a single current source could provide alone.

Inventive Principle:

Principle #1Segmentation

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 high-precision, temperature-compensated current that minimizes temperature dependence, enhancing the reliability of semiconductor circuits and maintaining accurate data retrieval while stabilizing oscillator periods.

Implementation Method 1

a first circuit employing transistors with a first emitter area ratio or diodes with a number ratio equivalent to the first emitter area ratio to generate a first current having a first temperature coefficient proportional to the absolute temperature

Methodology Applied

Scientific EffectProportional-to-Absolute-Temperature (PTAT) current generation:

Implementation Method 2

a second circuit employing transistors with a second emitter area ratio or diodes with a number ratio equivalent to the second emitter area ratio to generate a second current having a second temperature coefficient proportional to the absolute temperature

Methodology Applied

Scientific EffectProportional-to-Absolute-Temperature (PTAT) current generation:

Implementation Method 3

a differential circuit configured to output a differential current of the first current and the second current

Methodology Applied

Scientific EffectDifferential current subtraction:

Data Source

PatentUS11809207B2Temperature compensation circuit and semiconductor integrated circuit using the same

Publication Date: 2023.11.07 WINBOND ELECTRONICS CORP

AI summary

The disclosure provides a temperature compensation circuit that generates a temperature-compensated current and an integrated semiconductor circuit using the temperature compensation circuit. The temperature compensation circuit includes: a first PTAT current source which has a first emitter area ratio and generates a first current, the first current having a first temperature coefficient proportional to the absolute temperature; a second PTAT current source which has a second emitter area ratio and generates a second current, the second current having a second temperature coefficient proportional to the absolute temperature; an adjustment circuit which adjusts the current generated by the first PTAT current source; and a differential circuit which outputs the difference between the current adjusted by the adjustment circuit and the current generated by the second PTAT current source.