Closed-loop temperature compensation method and device for clock crystal oscillator

Abstract

The invention provides a closed-loop temperature compensation method and a closed-loop temperature compensation device for a clock crystal oscillator. A second pulse of a 32768Hz quartz crystal is continuously corrected by using an accurate high-frequency quartz crystal until the number of high-frequency pulses of a high-frequency pulse signal which is read in a time gate generated by the 32768Hz quartz crystal is equal to that of the high-frequency pulses which are theoretically accurate. Because the 32768Hz quartz crystal can be calibrated at any temperature, the frequency offset of the 32768Hz quartz crystal caused by temperature difference is compensated. In a closed-loop temperature compensation mode which is provided by the embodiment of the invention, the frequency temperature characteristic curve shape of a clock crystal is unrelated, and consistency is not required. Therefore, by adoption of a temperature soft compensation method provided by the invention, accurate temperature compensation can be realized. The cost of the temperature soft compensation method is low, and the size of a corresponding system is small.

Description

technical field [0001] The invention relates to the technical field of clock precision temperature compensation, in particular to a closed-loop temperature compensation method and device for a clock crystal oscillator. Background technique [0002] At present, in addition to standard sources with particularly high requirements, high-precision clock frequencies used in industry and daily life mainly come from quartz crystal oscillators. At present, the frequency of the quartz crystal oscillator used in clocks at home and abroad is 32768Hz. [0003] See attached figure 1 , the figure is the frequency temperature characteristic curve of 32768Hz quartz crystal oscillator. The frequency deviation ratio ΔF / F of the 32768Hz quartz crystal oscillator in the range of -30 to +60°C is about (+40)ppm to (-150)ppm (ppm means one millionth), so the clock error generated every day Up to 15 seconds or more. [0004] Therefore, if a higher clock accuracy is to be achieved, it is necessar...

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Problems solved by technology

[0007] At present, the cost of this soft compensation method is low, but because it is an open-loop compensation, the consistency of the frequency-temperature characteristic curve, the consistency of the temperature sensor, the consistency of the reference voltage of the A / D acquisition, and the manufacturing of the A / D acquisition circuit inside the MCU If there is a problem with any of the items such as consistency, the final compensation result cannot be guaranteed

If any one or more items are wrong, the compensation result will be inaccurate

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