Crystal Oscillator Bias Control for Low-Complexity Phase Noise Reduction
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Solution Overview
Problem
Existing crystal oscillators face challenges in reducing phase noise of the reference clock without introducing side effects, which affects the overall performance of electronic systems.
Innovation Solution
A crystal oscillator design incorporating a crystal oscillator core circuit, a bias circuit, and a phase noise reduction circuit that generates a sinusoidal wave and resets the bias voltage when it exceeds a specific range, thereby reducing phase noise without requiring calibration of the phase noise reset operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional circuits are added to reduce phase noise of the crystal oscillator, then phase noise performance is improved, but device complexity and implementation costs increase
Solution Approach 1:
The phase noise reduction circuit is merged with the existing bias circuit structure. The reset switch is integrated into the bias network, allowing phase noise reduction functionality to be combined with the existing biasing architecture rather than adding completely separate circuits.
Solution Approach 2:
The phase noise reduction circuit uses the oscillation signal itself to trigger the reset operation. When the oscillation voltage exceeds the threshold, it automatically activates the reset switch to discharge the coupling capacitor, creating a self-regulating phase noise reduction mechanism without requiring external control circuits.
2Reliability
If calibration circuits are added to calibrate the timing of phase noise reset operation, then phase noise reduction effectiveness is improved, but device complexity and costs increase
Solution Approach 1:
The oscillation signal itself serves as the trigger for phase noise reduction. When the oscillation voltage exceeds the threshold voltage, it automatically activates the reset switch without requiring external calibration or control circuits. The system self-regulates based on its own operating conditions.
Solution Approach 2:
The threshold voltage parameter is set to a specific value (e.g., 0.7V) that naturally corresponds to the oscillation signal characteristics. This parameter selection ensures that the reset operation occurs at the optimal moment in the oscillation cycle without requiring additional calibration circuits to adjust timing.
3Ease of manufacture
If a simple reset switch is used for phase noise reduction, then implementation costs are reduced, but phase noise reduction effectiveness may be insufficient without proper timing calibration
Solution Approach 1:
The oscillation signal automatically triggers the reset operation when it exceeds the threshold voltage, eliminating the need for complex calibration circuits. This self-regulating mechanism ensures that the simple reset switch achieves optimal phase noise reduction effectiveness without additional complexity.
Solution Approach 2:
The reset switch is activated periodically whenever the oscillation signal exceeds the threshold voltage, creating regular discharge events that effectively reduce phase noise. This periodic action occurs naturally at the optimal moments in the oscillation cycle, maintaining effectiveness without requiring calibration.
Data Source
AI summary
A crystal oscillator and a phase noise reduction method thereof are provided. The crystal oscillator may include a crystal oscillator core circuit, a first bias circuit and a phase noise reduction circuit, the first bias circuit is coupled to an output terminal of the crystal oscillator core circuit, and the phase noise reduction circuit is coupled to the output terminal of the crystal oscillator core circuit. In operations of the crystal oscillator, the crystal oscillator core circuit is configured to generate a sinusoidal wave. The first bias circuit is configured to provide a first voltage level to be a bias voltage of the sinusoidal wave. The phase noise reduction circuit is configured to reset the bias voltage of the sinusoidal wave in response to a voltage level of the sinusoidal wave exceeding a specific voltage range.