Fast Start-Up Crystal Oscillator Using Pre-Calibrated VCO Division
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Solution Overview
Problem
Existing crystal oscillator start-up methods are sensitive to temperature variations, requiring time-consuming calibration and increased hardware resources, making them inefficient for frequent wake-up modes in communications devices.
Innovation Solution
A fast start-up crystal oscillator architecture comprising a core circuit, frequency synthesizer, and interfacing circuit, where the frequency synthesizer includes a voltage control oscillator (VCO) and divider, allowing for calibration of the VCO frequency using a reference clock to reduce sensitivity to temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If calibration of start-up settings is performed when XO enters wakeup mode from sleep mode, then temperature variation impact is compensated, but calibration time is too long for frequent wake-up operations
Solution Approach 1:
The patent performs calibration during manufacturing before the product is shipped, so that the start-up settings are pre-calibrated and stored in memory. When the XO enters wakeup mode from sleep mode, the pre-calibrated settings are directly applied without requiring time-consuming recalibration, thus resolving the contradiction between temperature compensation reliability and calibration time loss
Solution Approach 2:
The patent creates a copy of the calibrated start-up settings during manufacturing and stores it in memory. This copied configuration is then reused during wake-up operations instead of performing full calibration each time, eliminating the time penalty while maintaining temperature compensation effectiveness
2Reliability
If trimming regarding temperature-affected components is performed to ensure start-up performance, then temperature sensitivity is reduced, but hardware resources and measurement tasks are greatly increased
Solution Approach 1:
The patent makes the system self-service by automatically applying the pre-calibrated start-up settings during wake-up operations without requiring external trimming or additional hardware resources. The calibrated values stored in memory are automatically loaded and used, eliminating the need for complex trimming circuits and measurement tasks while ensuring temperature-compensated start-up performance
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
This approach significantly shortens calibration time and reduces sensitivity to temperature fluctuations, improving the robustness of the start-up procedure without increasing overall costs or introducing side effects.
Implementation Method 1
the frequency synthesizer may comprise a voltage control oscillator (VCO) and a divider coupled to the VCO. The VCO is configured to generate a VCO clock having a VCO frequency
Implementation Method 2
the divider is configured to generate a divided clock having a divided frequency, wherein the VCO frequency is divided by a divisor of the divider to obtain the divided frequency
Data Source
AI summary
A fast start-up crystal oscillator (XO) and a fast start-up method thereof are provided. The fast start-up XO may include a XO core circuit, a frequency synthesizer, and a fast start-up interfacing circuit, wherein the frequency synthesizer may include a voltage control oscillator (VCO) and a divider. The XO core circuit generates a XO signal having a XO frequency. The VCO generates a VCO clock having a VCO frequency, and the divider generates a divided clock having a divided frequency, wherein the VCO frequency is divided by a divisor of the divider to obtain the divided frequency. The fast start-up interfacing circuit transmits the divided clock to the XO core circuit, and then generates a reference clock having the XO frequency according to the XO signal. More particularly, the VCO frequency is calibrated according to the reference clock, in order to make the divided frequency approach the XO frequency.