Temperature-Compensated Clock Circuit Using Dynamic Division Ratio
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Solution Overview
Problem
Quartz oscillators used in electronic circuits are sensitive to temperature variations, leading to degraded accuracy of clock signals in real-time clock systems, which existing compensation methods, such as adjusting frequency or modifying clock pulses, only achieve accuracy of up to 3-5 ppm.
Innovation Solution
A circuit and method that includes a frequency divider, a temperature compensation circuit to generate a division ratio based on measured temperature, and a control system to adjust a calibration element's connection to the oscillator, thereby improving the accuracy of the clock signal by compensating for temperature-induced frequency changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a crystal oscillator is used to generate a clock signal, then the frequency precision is improved, but the accuracy degrades under temperature variations
Solution Approach 1:
The patent changes the division ratio parameter dynamically based on temperature measurements. The temperature compensation circuit measures temperature and adjusts the division ratio to compensate for frequency drift, transforming a static parameter into a dynamic one that adapts to environmental conditions.
Solution Approach 2:
The patent implements a feedback mechanism where the temperature compensation circuit continuously monitors temperature and feeds back adjustment signals to modify the division ratio. This closed-loop control ensures the clock signal accuracy is maintained by counteracting temperature-induced frequency variations.
2Measurement precision
If additional capacitive load is added across a crystal to adjust frequency, then the frequency accuracy is improved, but the device complexity increases
Solution Approach 1:
Instead of physically changing capacitive loads, the patent changes the electrical division ratio parameter through digital control. This achieves frequency compensation by modifying the frequency division relationship rather than the oscillator's physical characteristics, reducing circuit complexity.
Solution Approach 2:
The patent replaces the mechanical/electrical approach of adjusting physical capacitive loads with an electronic/digital approach using a programmable frequency divider. The control system electronically adjusts the division ratio based on temperature, substituting physical component adjustment with digital parameter modification.
3Measurement precision
If clock pulses are deleted or inserted to modify frequency periodically, then the time accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent changes the division ratio parameter to achieve frequency compensation, which is a simpler and more continuous method compared to periodic pulse deletion or insertion. This parameter adjustment occurs smoothly based on temperature measurements rather than through discrete pulse manipulation.
Solution Approach 2:
The patent replaces the complex mechanism of periodically deleting or inserting clock pulses with a continuous parameter adjustment of the division ratio. This substitution uses electronic parameter modification instead of mechanical pulse manipulation, reducing control complexity while achieving similar accuracy improvement.
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 achieves higher accuracy in clock signal generation by dynamically adjusting the division ratio and calibration element connection, enhancing the stability of the clock signal across varying temperatures.
Implementation Method 1
a temperature compensation circuit to measure a temperature of the oscillator
Implementation Method 2
A crystal oscillator is an electronic circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency
Implementation Method 3
a frequency divider to divide the oscillating signal by the division ratio into a clock signal
Data Source
AI summary
A circuit comprises a frequency divider coupled to receive an oscillating signal generated by an oscillator and a division ratio and configured to divide the oscillating signal by the division ratio into a clock signal; a temperature compensation circuit configured to measure a temperature of the oscillator and generate a division ratio to be provided to the frequency divider and a first value on the basis of the measured temperature; and a control system configured to control connection between a calibration element and the oscillator based on the first value and the oscillating signal of the oscillator.