Temperature-Compensated Voltage Circuit for Crystal Oscillator Drift

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Solution Overview

Problem

Existing temperature-compensated voltage generating circuits for crystal oscillator modules face challenges in maintaining stable oscillation frequency due to temperature differences between the oscillator element and the temperature detecting circuit, leading to frequency errors when the temperature change is slow.

Innovation Solution

A temperature-compensated voltage generating circuit that includes a temperature detecting circuit, a high frequency attenuating part, and a compensated voltage generating part, which attenuates high frequency components of the temperature signal to generate a voltage matching the oscillator element's temperature, thereby reducing frequency errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a temperature sensor is used to detect temperature for frequency compensation, then frequency stability can be improved, but frequency errors occur when the temperature change of the crystal resonator is slower than the temperature sensor

Engineering Contradiction:

Improvefrequency stabilityVSAvoidtemperature measurement accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

A low-pass filter is introduced as an intermediary between the temperature sensor and the compensation circuit. This filter mediates the temperature signal by attenuating high-frequency components, allowing the compensation circuit to respond smoothly to temperature changes without overreacting to rapid sensor fluctuations, thus resolving the timing mismatch between sensor and resonator temperature changes

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the frequency parameter of the temperature signal by filtering out high-frequency components. This parameter transformation converts the raw temperature sensor output into a smoothed signal that better matches the thermal response characteristics of the crystal resonator, eliminating frequency errors caused by differential heating rates

Inventive Principle:

Principle #35Parameter changes

2Speed

If high frequency components of temperature signal are used for compensation, then response speed is improved, but frequency errors increase due to mismatch with oscillator element temperature

Engineering Contradiction:

Improvetemperature response speedVSAvoidfrequency accuracy

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The low-pass filter acts as a mediator that selectively removes high-frequency components from the temperature signal. This intermediary processing ensures that only the relevant low-frequency temperature variations are used for compensation, matching the thermal inertia characteristics of the crystal resonator and preventing frequency errors

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies partial action by selectively attenuating only the high-frequency portion of the temperature signal while preserving the low-frequency components. This partial filtering approach maintains adequate response speed for temperature compensation while eliminating the excessive high-frequency content that causes frequency errors

Inventive Principle:

Principle #16Partial or excessive action

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 proposed solution effectively reduces oscillation frequency errors by generating a temperature-compensated voltage that aligns with the oscillator element's temperature, even during slow temperature changes, ensuring stable frequency output.

Implementation Method 1

a high frequency attenuating part that attenuates at least a part of a frequency component which is higher than a direct-current component of an output of the temperature detecting circuit

Methodology Applied

Scientific EffectHigh frequency attenuation: Filter (electronic)

Data Source

PatentUS10819346B2Temperature-compensated voltage generating circuit, oscillator module, system and method

Publication Date: 2020.10.27 ASAHI KASEI MICRODEVICES CORP

AI summary

Provided is a temperature-compensated voltage generating circuit that generates a temperature-compensated voltage which is supplied to an oscillator circuit. The temperature-compensated voltage generating circuit includes a temperature detecting circuit that detects a temperature; a high frequency attenuating part that attenuates at least a part of a frequency component which is higher than a direct-current component of an output of the temperature detecting circuit; an adder that adds the output of the temperature detecting circuit and an output of the high frequency attenuating part; and a compensated voltage generating part that generates the temperature-compensated voltage based on an output of the adder.