Crystal Oscillator Startup Using Calibrated Auxiliary Injection
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Solution Overview
Problem
Existing crystal oscillator startup methods are sensitive to temperature variations, leading to increased startup time and circuit area when using passive devices to mitigate this sensitivity.
Innovation Solution
A crystal oscillator architecture that includes a core circuit, an auxiliary oscillator, and a frequency detection circuit with a resistive circuit, where the auxiliary oscillator is calibrated using the XO signal as a reference during the first phase, and the resistive circuit is calibrated to generate a detection voltage, allowing the driving signal to be injected during the second phase to accelerate startup, while maintaining frequency accuracy across temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If passive devices such as inductors are used to reduce temperature sensitivity, then temperature stability is improved, but circuit area is greatly increased
Solution Approach 1:
The patent replaces passive inductive devices with an active digital calibration system. Instead of using temperature-insensitive passive components (inductors), the invention uses a digitally controlled oscillator with calibration circuits that actively compensate for temperature effects through frequency adjustment, thereby achieving temperature stability without the area penalty of passive devices
Solution Approach 2:
The patent changes the operating parameters of the oscillator by implementing a calibration mechanism that adjusts the oscillation frequency based on temperature conditions. The calibration circuits modify the oscillator parameters (frequency, phase) to maintain stable operation across temperature variations, replacing the need for temperature-insensitive passive components
2Productivity
If fast startup methods are used to reduce wakeup time, then productivity is improved, but temperature sensitivity increases
Solution Approach 1:
The patent applies preliminary calibration actions before the oscillator enters fast startup mode. The calibration circuits pre-adjust the oscillator parameters based on expected temperature conditions, so that when fast startup is initiated, the oscillator is already optimized for the current temperature environment, achieving both fast startup and temperature insensitivity
Solution Approach 2:
The patent implements feedback mechanisms where the calibration circuits continuously monitor oscillator performance and adjust parameters in response to temperature changes. This feedback loop ensures that the fast startup method remains effective across varying temperature conditions by dynamically compensating for temperature effects
Data Source
AI summary
A crystal oscillator (XO) and a method for performing startup of the XO are provided. The XO includes a XO core circuit, an auxiliary oscillator and a frequency detection circuit, wherein the frequency detection circuit includes a resistive circuit. The frequency detection circuit generates a detection voltage according to a driving signal associated with an auxiliary signal generated by the auxiliary oscillator and a first impedance of the resistive circuit. During a first powered on phase, the auxiliary oscillator is calibrated by utilizing the XO core circuit as a reference after startup of the XO core circuit is completed, and the resistive circuit is calibrated according to the detection voltage. During a second powered on phase, a frequency of the driving signal is calibrated according to the detection voltage, and the driving signal is injected to the XO core circuit for accelerating the startup of the XO core circuit.