GPSDO Crystal Oscillator Retrace Correction at Power-On
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Solution Overview
Problem
Crystal oscillators, particularly GPSDOs, experience significant frequency drift, known as retrace, immediately after power-on, leading to phase or frequency errors that can cause malfunction in communication equipment.
Innovation Solution
A method that establishes an operating baseline for the crystal oscillator by measuring and storing frequency control signals, then adjusts the frequency using error correction signals to compensate for retrace errors, even in the absence of an external frequency reference, by applying a retrace correction voltage based on predictive models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the crystal oscillator operates immediately after power-on, then the device can start functioning quickly, but significant frequency drift (retrace) occurs causing phase or frequency errors
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing retrace correction values in a lookup table during manufacturing or initial calibration. When the oscillator powers on, these pre-computed correction values are immediately applied to compensate for expected frequency drift, eliminating the need for time-consuming real-time measurements and calculations during startup.
Solution Approach 2:
The patent implements beforehand cushioning by pre-determining the magnitude and timing of retrace effects through characterization tests, then storing compensatory correction values in advance. This creates a buffer against frequency errors before they occur, allowing the oscillator to maintain accuracy immediately upon power-on without experiencing significant drift.
2Reliability
If retrace correction is applied using real-time measurements and calculations, then frequency accuracy improves, but the complexity of the correction system increases
Solution Approach 1:
The patent eliminates real-time measurement and calculation complexity by pre-computing all necessary retrace correction values during manufacturing or initial calibration. The lookup table stores pre-determined correction values that can be directly applied without requiring complex algorithms, sensors, or processors during operation, significantly reducing system complexity while maintaining high accuracy.
Solution Approach 2:
The patent uses a simple lookup table structure that requires minimal hardware resources compared to complex real-time correction systems. The correction data is stored in non-volatile memory and retrieved as needed, replacing the need for expensive and complex real-time measurement and calculation infrastructure.
3Reliability
If the oscillator waits for stabilization before operation, then frequency accuracy improves, but the time to reach operational state increases significantly
Solution Approach 1:
The patent applies preliminary action by pre-calculating retrace correction values and storing them in a lookup table before the oscillator needs to operate. This allows the device to immediately apply accurate frequency compensation upon power-on, eliminating the need to wait for stabilization while maintaining high frequency accuracy from the start.
Solution Approach 2:
The patent implements preliminary anti-action by pre-determining and storing correction values that counteract expected retrace effects. This allows the oscillator to proactively compensate for frequency drift before it occurs, rather than waiting for stabilization or reacting to errors after they manifest, thus achieving both immediate operation and high accuracy.
Data Source
AI summary
In one embodiment, the present invention includes a method of correcting the frequency of a crystal oscillator. The method includes establishing an operating baseline for the crystal oscillator using a frequency reference, storing information in memory, and adjusting the frequency according to the information. The information corresponds to the operating baseline. Adjusting the frequency occurs in response to a power-on event and the absence of the frequency reference.