Crystal Oscillator Startup Timing for Comparator Dispersion
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Solution Overview
Problem
Conventional crystal oscillators face precision issues due to comparator dispersion, which affects the accuracy of phase information during startup, as the switching delay of the comparator is amplitude-dependent, leading to potential false phase determination.
Innovation Solution
A crystal oscillator design that includes a startup controller generating a sequence of excitation signals, a comparator with digital storage to characterize switching delays, and a phase shifting unit to compensate for dispersion by modifying timing signals based on stored data, ensuring precise phase determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a comparator is used to detect the phase of the signal on the crystal resonator, then the startup speed of the oscillator is improved, but the precision of phase information is degraded due to comparator dispersion
Solution Approach 1:
The patent implements a feedback mechanism where the measured switching delay of the comparator is fed back to adjust the sampling timing. The system measures the actual switching delay at different signal amplitudes during startup and uses this information to compensate for the dispersion effect, thereby maintaining both fast startup and accurate phase measurement.
Solution Approach 2:
The patent changes the operating parameters by measuring and compensating for comparator switching delay as a function of signal amplitude. By dynamically adjusting the phase determination based on the actual signal amplitude and corresponding switching delay characteristics, the system resolves the contradiction between fast startup (high amplitude) and precise measurement (stable amplitude).
2Speed
If the switching delay of the comparator is amplitude-dependent, then the response speed varies with signal strength, but the phase determination accuracy is compromised
Solution Approach 1:
The system continuously monitors the switching delay of the comparator at different signal amplitudes and uses this feedback information to correct the phase determination. By establishing a relationship between signal amplitude and switching delay, the system can compensate for the amplitude-dependent variations and maintain accurate phase measurement throughout the startup process.
Solution Approach 2:
The patent replaces direct mechanical timing measurement with an electronic compensation approach. Instead of relying on fixed timing circuits, the system uses digital processing to measure and compensate for the comparator's switching delay characteristics, substituting rigid mechanical timing with flexible electronic correction.
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
The solution effectively compensates for comparator dispersion, improving the precision of phase determination and reducing the detrimental impact on phase information, allowing for accurate startup and operation of the crystal oscillator.
Implementation Method 1
A crystal oscillator is an electronic oscillating circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electric signal with a precise frequency
Implementation Method 2
a comparator operable to provide a comparative signal
Data Source
AI summary
A crystal oscillator and a startup method for initiating operation of a crystal oscillator, the crystal oscillator includes an oscillator structure including a crystal resonator and an electronic oscillator circuit connected to the crystal resonator, the oscillator structure having a first terminal and a second terminal, a startup controller operable to initiate an oscillation in the oscillator structure by exciting the oscillator structure with a sequence of excitation signals derivable from a clock signal and when triggered by a timing signal, the sequence of excitation signals includes at least a first excitation signal and a second excitation signal, a comparator including a first and a second input terminal and an output terminal, the first input terminal being connected to the first terminal and wherein the second input terminal is connected to the second terminal.