Crystal Oscillator Startup Using Adaptive Multi-Phase Injection
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Solution Overview
Problem
In portable electronic devices, the power consumption is significantly affected by the time it takes for the crystal oscillator to stabilize, and existing methods to accelerate startup are limited by the need for precise frequency matching of the driving clock signal with the crystal oscillator, which is challenging due to process bias, temperature, and voltage variations.
Innovation Solution
A circuit and method that includes a multi-phase oscillator, phase selection circuit, and drive circuit to generate and select candidate clock signals, calibrate the frequency of the multi-phase oscillator to match the crystal oscillator, and inject the selected clock signal to rapidly start the crystal oscillator, using a comparator, counter, index circuit, and multiplexer to ensure phase alignment and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a clock signal with frequency close to the crystal oscillator is injected to accelerate startup, then the startup speed is improved, but the reliability deteriorates due to frequency mismatch caused by process bias, temperature, and voltage variations
Solution Approach 1:
The patent applies dynamics by making the injection signal frequency adaptive rather than fixed. The system dynamically adjusts the injection signal frequency to track the crystal oscillator frequency under varying conditions (process bias, temperature, voltage), transforming a static frequency mismatch problem into a dynamic tracking solution that maintains reliability while achieving fast startup
Solution Approach 2:
The patent implements feedback by using the crystal oscillator's output signal to generate the injection signal. The phase detector continuously monitors the phase difference between the crystal oscillator and injection signal, and this feedback information is used to adjust the injection signal frequency, ensuring it remains synchronized with the crystal oscillator despite environmental variations
2Stability of the object's composition
If the drive circuit operates continuously to maintain crystal oscillator stability, then the stability is improved, but the power consumption increases
Solution Approach 1:
The patent applies periodic action by operating the drive circuit in periodic bursts rather than continuously. The control circuit enables the drive circuit only during specific periods when the crystal oscillator needs boosting, and disables it during other periods, thereby maintaining stability through periodic reinforcement while significantly reducing average power consumption
Solution Approach 2:
The system implements self-service by using the crystal oscillator's own output signal to generate the injection signal through the phase-locked loop circuitry. The crystal oscillator effectively serves itself by providing the reference signal that drives the injection mechanism, eliminating the need for an external high-precision frequency source and reducing overall system power consumption
Data Source
AI summary
Embodiments of circuits and methods for starting a crystal oscillator are disclosed herein. In one example, an oscillation circuit is disclosed. The oscillation circuit includes a multi-phase oscillator, a control circuit, a phase selection circuit, a drive circuit, and a crystal oscillator. The multi-phase oscillator is configured to generate candidate clock signals of multiple phases. The phase selection circuit is coupled to the multi-phase oscillator and configured to select a clock signal from the candidate clock signals. The drive circuit is coupled to the phase selection circuit and configured to inject the selected clock signal to the crystal oscillator for a period of time determined by the control circuit. The control circuit is coupled to the phase selection circuit and the drive circuit and is configured to control the on and off of the drive circuit and output a plurality of injections signals.