Dual-Oscillator Clock Calibration for Low-Power Accuracy

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing embedded systems, particularly sensor nodes, face challenges in providing a reliable and accurate clock source with reduced power consumption, as conventional oscillators either consume high power or operate at low frequencies due to stability requirements.

Innovation Solution

The implementation of a dual-oscillator system comprising a temperature-compensated on-chip digitally controlled oscillator (OSCCMP) and an uncompensated oscillator (OSCUCMP), where the OSCCMP provides stability and the OSCUCMP operates at ultra-low power, with a comparator circuit to synchronize and adjust the OSCUCMP output based on environmental changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a crystal oscillator (XTAL) is used to provide an accurate clock source, then clock stability and accuracy are improved, but power consumption increases significantly

Engineering Contradiction:

Improveclock accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The system is divided into two oscillator segments: a low-power uncompensated oscillator for normal operation and a high-accuracy compensated oscillator for calibration. This segmentation allows the system to achieve high accuracy without continuously operating the power-hungry compensated oscillator, thus resolving the contradiction between clock accuracy and power consumption.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The compensated oscillator operates periodically to calibrate the uncompensated oscillator rather than continuously. The system intermittently activates the compensated oscillator to adjust the uncompensated oscillator's frequency, maintaining accuracy while minimizing power consumption by keeping the compensated oscillator dormant most of the time.

Inventive Principle:

Principle #19Periodic action

2Stability of the object's composition

If a compensated oscillator is used to achieve temperature stability, then clock stability under environmental changes is improved, but power consumption increases

Engineering Contradiction:

Improvetemperature stabilityVSAvoidpower consumption

Core Design Contradiction:

Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The compensated oscillator performs preliminary calibration of the uncompensated oscillator to establish accurate operating parameters before the system enters normal low-power mode. This preliminary action ensures temperature stability is configured in advance, allowing the uncompensated oscillator to maintain stability without continuous compensation, thus reducing ongoing power consumption.

Inventive Principle:

Principle #10Preliminary action

3Use of energy by moving object

If an uncompensated oscillator is used to reduce power consumption, then power consumption is reduced, but clock accuracy deteriorates under environmental changes

Engineering Contradiction:

Improvepower consumptionVSAvoidclock accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The system implements a feedback mechanism where the compensated oscillator periodically measures the frequency drift of the uncompensated oscillator and provides correction signals. This feedback loop allows the low-power uncompensated oscillator to maintain accuracy by receiving periodic adjustments based on actual performance, resolving the contradiction between low power consumption and maintained accuracy.

Inventive Principle:

Principle #23Feedback

4Measurement precision

If a crystal oscillator is used for precise data sampling and RF modulation, then measurement precision is improved, but device complexity increases due to off-chip components

Engineering Contradiction:

Improvedata sampling precisionVSAvoidnumber of off-chip components

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the functions of the crystal oscillator and temperature compensation circuitry into a single integrated on-chip oscillator module. By combining these previously separate off-chip components into one integrated unit, the system maintains precise data sampling and RF modulation capabilities while reducing device complexity and eliminating the need for external passive components.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS9590638B2Low power clock source

Publication Date: 2017.03.07 UNIV OF VIRGINIA PATENT FOUND

AI summary

An ultra-low power clock source includes a compensated oscillator and an uncompensated oscillator coupled by a comparator circuit. In an example, the compensated oscillator is more stable than the uncompensated oscillator with respect to changes in one or more of temperature, voltage, age, or other environmental parameters. The uncompensated oscillator includes a configuration input configured to adjust an operating characteristic of the uncompensated oscillator. In an example, the uncompensated oscillator is adjusted using information from the comparator circuit about a comparison of output signals from the compensated oscillator and the uncompensated oscillator.