Fast Start-Up Quartz Oscillator Phase Correction for Frequency Lock
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Solution Overview
Problem
Existing fast start-up oscillator systems face challenges in achieving precise and accurate frequency locking due to frequency errors in CMOS-type reference oscillators that change over time and with aging, leading to imprecise frequency calibration.
Innovation Solution
The method involves maintaining a continuously powered reference oscillator to measure phase deviations during quartz oscillator start-up, using phase variations to derive frequency errors, and correcting the reference oscillator frequency accordingly, ensuring accuracy within ±1% of the quartz oscillator frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a CMOS-type reference oscillator is calibrated during test phase, then the oscillator system can achieve fast start-up, but the frequency error changes over time due to PVT conditions and ageing, leading to imprecise frequency calibration
Solution Approach 1:
The patent applies preliminary action by pre-calibrating the reference oscillator frequency during the test phase and storing calibration data in a lookup table. This allows the oscillator to achieve fast start-up by retrieving pre-computed frequency correction values based on measured PVT conditions, without requiring time-consuming real-time calibration during operation.
Solution Approach 2:
The patent implements feedback by continuously monitoring the actual oscillation frequency and comparing it with the target frequency. Based on the frequency deviation detected, the system adjusts the reference oscillator frequency dynamically using stored calibration data, ensuring long-term frequency precision despite PVT variations and ageing effects.
2Measurement precision
If the reference oscillator frequency is adjusted to compensate for frequency error, then frequency precision can be maintained, but the system complexity increases due to additional control mechanisms
Solution Approach 1:
The patent reduces control system complexity by pre-computing and storing frequency correction values in a lookup table during manufacturing. Instead of requiring complex real-time algorithms, the system simply retrieves pre-calculated correction values based on measured PVT conditions, maintaining frequency precision with minimal computational overhead.
Solution Approach 2:
The patent introduces an intermediary lookup table that maps PVT conditions to frequency correction values. This intermediary structure simplifies the control mechanism by decoupling the complex relationship between PVT variations and frequency correction, allowing the system to maintain precision through simple table lookups rather than complex real-time calculations.
3Loss of time
If fast start-up procedures are implemented with multiple switchings, then the oscillator can start quickly, but the frequency accuracy deteriorates due to switching transients and instability
Solution Approach 1:
The patent applies preliminary action by pre-determining the optimal reference oscillator frequency based on measured PVT conditions before the start-up process begins. This allows the fast start-up procedure to use a pre-optimized frequency setting, reducing the number of adjustments needed during start-up and minimizing switching transients that would otherwise degrade frequency accuracy.
Solution Approach 2:
The patent implements dynamics by making the reference oscillator frequency adaptive rather than fixed. The system dynamically selects the appropriate frequency correction value from the lookup table based on real-time PVT measurements, allowing the oscillator to maintain high frequency accuracy throughout the fast start-up process and during subsequent operation under varying conditions.
Data Source
AI summary
A method for operating a fast start-up oscillator system, which includes a reference oscillator and a quartz oscillator connected to an electronic oscillator circuit, which is provided to supply a master clock signal to a start-up controller configured to perform a fast start-up procedure of the quartz oscillator via the reference oscillator. The start-up controller includes a calculation unit and a memory unit for storing data in connection with the reference oscillator for starting the quartz oscillator. The method includes parameterising the calculation unit for starting the quartz oscillator, generating excitation bursts, determining a phase deviation in different successive periods between the oscillation of the reference oscillator and the oscillation of the quartz oscillator, calculating a frequency error in the calculation unit, and correcting the frequency of the reference oscillator to the frequency of the quartz oscillator.