Crystal Oscillator Startup with Comparator Delay Compensation
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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, 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 to provide comparative signals, and a digital storage to store switching delay data, allowing a phase shifting unit to compensate for comparator dispersion by using digital offset values derived from a lookup table or calibration mode.
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 is improved, but the measurement precision deteriorates due to comparator dispersion affecting phase information accuracy
Solution Approach 1:
The patent uses feedback by measuring the actual switching delay of the comparator during startup and using this measured delay to compensate for phase determination errors. The system continuously monitors the comparator's performance and adjusts phase calculations based on the observed dispersion, thereby maintaining both fast startup and accurate phase measurement.
Solution Approach 2:
The patent changes the parameter approach by not treating the comparator switching delay as a fixed constant, but rather as a variable parameter that is measured and compensated for in real-time. This allows the system to adapt to the actual comparator behavior and correct phase determination errors dynamically during the startup process.
2Speed
If the switching delay of the comparator is reduced to improve phase detection speed, then the startup speed is improved, but the reliability deteriorates due to potential false phase determination
Solution Approach 1:
The system implements feedback by measuring the actual switching delay and using this information to correct phase determination. This feedback mechanism ensures that even with fast switching, the phase detection remains reliable by compensating for any delays that occur.
Solution Approach 2:
The patent performs preliminary measurement of the comparator switching delay before using the comparator for phase determination. This preliminary action allows the system to prepare compensation values in advance, ensuring that phase detection is both fast and reliable from the start of the startup process.
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 effectively reduces the impact of comparator dispersion, improving the precision of phase determination and ensuring accurate startup 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
The comparator is operable to provide a comparative signal... The comparator comprises a first input terminal and a second input terminal... The first input terminal is connected to the first terminal of the oscillator structure. The second input terminal of the comparator is connected to the second terminal of the oscillator structure
Implementation Method 3
The phase shifting unit is operable to generate the timing signal on the basis of the comparative signal and on the basis of the digital data provided by the digital storage... allowing a phase shifting unit to compensate for comparator dispersion
Data Source
Figure 1
Figure 2~4
AI summary
The disclosure concerns a crystal oscillator and a startup method for initiating operation of a crystal oscillator, the crystal oscillator comprises: - an oscillator structure (11) comprising a crystal resonator (12) and an electronic oscillator circuit (14) connected to the crystal resonator (12), the oscillator structure (11) having a first terminal (13) and a second terminal (15), - a startup controller (16) operable to initiate an oscillation in the oscillator structure (11) by exciting the oscillator structure (11) with a sequence of excitation signals (110, 112, 114) derivable from a clock signal and when triggered by a timing signal, the sequence of excitation signals includes at least a first excitation signal (110) and a second excitation signal (112), - a comparator (30) comprising a first and a second input terminal (31, 32) and an output terminal (33), wherein the first input terminal (31) is connected to the first terminal (13) and wherein the second input terminal (32) is connected to the second terminal (15), the comparator (30) being operable to provide a comparative signal, characterized by - a digital storage (27) configured to store digital data characterizing a switching delay of the comparator (30) and - a phase shifting unit (70) coupled to the digital storage (27) and coupled to the output terminal (33) of the comparator (30), the phase shifting unit (70) being operable to generate or to modify the timing signal on the basis of the comparative signal and on the basis of the digital data provided by the digital storage (27).