Crystal Oscillator Startup with AM-Guided External Clock Injection
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Solution Overview
Problem
Crystal oscillators (XOs) in communication devices face a bottleneck in startup time, which is power-consuming and hinders efficient communication, especially when transitioning from sleep mode to active mode, as existing methods to reduce startup time often increase power consumption.
Innovation Solution
The method involves using an external oscillator with a lower quality factor to inject energy into the XO core circuit through an injection switch, generating a modulation signal that adjusts the injection frequency to accelerate startup without significant additional power consumption, utilizing a monitoring circuit to optimize the relative phase and ensure efficient clock injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the startup time of the XO is reduced by controlling negative resistance within the XO, then the startup speed is improved, but additional power consumption increases
Solution Approach 1:
An external oscillator is introduced as an intermediary component to inject clock signals into the XO core circuit. This external oscillator assists the XO in starting up by providing an initial clock signal that accelerates the startup process without requiring the XO to generate the signal from scratch, thereby reducing startup time while avoiding the need to increase negative resistance control power consumption within the XO itself.
2Use of energy by moving object
If the XO enters sleep mode to save power, then power consumption is reduced, but startup time becomes a bottleneck when waking up
Solution Approach 1:
The external oscillator performs preliminary action by generating and injecting clock signals into the XO core circuit before the XO is fully started up from sleep mode. This preliminary injection of energy and timing signals prepares the XO for rapid startup, allowing it to quickly transition from sleep mode to active operation without incurring excessive power consumption or startup delay.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces the overall startup time of the XO while maintaining efficiency and minimizing power consumption, optimizing performance without introducing side effects.
Implementation Method 1
turning on the at least one injection switch to make energy of the injected signal be injected into the XO core circuit, thereby increasing energy of an intrinsic oscillation signal of the XO core circuit
Implementation Method 2
controlling the external oscillator to selectively change an injection frequency of the injected signal according to the modulation signal
Data Source
AI summary
A method for startup of a crystal oscillator (XO) with aid of external clock injection, associated XO and a monitoring circuit therein are provided. The XO includes an XO core circuit, an external oscillator, and an injection switch, where a quality factor of the external oscillator is lower than a quality factor of the XO core circuit. The method includes: utilizing the external oscillator to generate an injected signal; turning on the injection switch to make energy of the injected signal be injected into the XO core circuit, where an amplitude modulation (AM) signal is generated according to combination of the injected signal and an intrinsic oscillation signal from the XO core circuit; and controlling the external oscillator to selectively change an injection frequency of the injected signal according to the AM signal. More particularly, the injection switch is not turned off until the startup process is completed.