Bandgap Reference Circuit for RC Oscillator Temperature Compensation

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Solution Overview

Problem

Existing oscillator circuits, particularly RC oscillators, face challenges in maintaining accurate and constant frequency output due to the temperature coefficient of resistivity, which affects the clock signal period and stability across varying temperatures.

Innovation Solution

A bandgap reference circuit with a resistivity temperature coefficient cancellation circuit is implemented, generating temperature-insensitive reference voltage and current, and a temperature-compensated oscillator circuit that uses a digital duty trimmer to adjust the duty ratio of the clock signal, thereby stabilizing the frequency output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a resistance-capacitor (RC) oscillator is used to generate clock signals, then the circuit structure is simple and easy to manufacture, but the frequency output is affected by temperature coefficient of resistivity causing frequency fluctuations

Engineering Contradiction:

Improvecircuit structure simplicityVSAvoidfrequency stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent uses a bandgap reference circuit to generate temperature-insensitive reference voltage and current by canceling temperature coefficients. The resistivity temperature coefficient cancellation circuit removes the temperature-dependent component from the reference current, ensuring stable frequency output across temperature variations while maintaining RC oscillator simplicity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements a feedback mechanism where the bandgap reference circuit continuously monitors and compensates for temperature effects on the reference current. The resistivity temperature coefficient cancellation circuit uses feedback to eliminate the temperature-dependent portion of the current, maintaining stable frequency without complex circuit changes

Inventive Principle:

Principle #23Feedback

2Reliability

If temperature compensation is implemented using traditional methods, then frequency stability is improved, but the device complexity increases

Engineering Contradiction:

Improvefrequency stabilityVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The bandgap reference circuit performs multiple functions simultaneously: generating a temperature-insensitive reference voltage, generating a temperature-insensitive reference current, and providing temperature compensation. The resistivity temperature coefficient cancellation circuit integrates these functions to achieve frequency stability without adding separate compensation circuits

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the voltage reference and current reference generation into a single bandgap reference circuit structure. The resistivity temperature coefficient cancellation is integrated within the same circuit block, combining multiple temperature compensation functions into one unified structure rather than separate circuits

Inventive Principle:

Principle #5Merging (Combining)

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 effectively cancels the temperature coefficient of resistivity, ensuring a stable and accurate frequency output across temperature variations, enhancing the precision and reliability of oscillator circuits in electronic devices.

Implementation Method 1

a bandgap reference circuit including a reference current generation circuit, a resistivity temperature coefficient cancellation circuit, and a reference voltage generation circuit

Methodology Applied

Scientific EffectTemperature coefficient cancellation:

Implementation Method 2

The resistivity temperature coefficient cancellation circuit is configured to remove a first current proportional to temperature from the bandgap reference current by using the third voltage

Methodology Applied

Scientific EffectOhm's law: Ohm's Law

Data Source

PatentUS11789482B2Bandgap reference circuit including resistivity temperature coefficient cancellation circuit, and oscillator circuit including the bandgap reference circuit

Publication Date: 2023.10.17 SAMSUNG ELECTRONICS CO LTD

AI summary

A bandgap reference circuit includes a reference current generation circuit configured to output a bandgap reference current insensitive to a temperature change, by using a first voltage inversely proportional to temperature and a third voltage proportional to temperature. The third voltage is a difference between the first voltage and a second voltage. The bandgap reference circuit further includes a resistivity temperature coefficient cancellation circuit configured to remove a first current proportional to temperature from the bandgap reference current by using the third voltage, and a reference voltage generation circuit configured to output a bandgap reference voltage insensitive to a temperature change by using a second current inversely proportional to temperature and a first resistance proportional to temperature. The second current is generated by removing the first current from the bandgap reference current.