Precise Clock Circuit Design

Nowadays,electronic products are various,and many factors determine the performance of electronic products.Among them,clock source is a key factor.Clock source is like the heart of electronic equipment.If electronic equipment wants to operate normally,clock source is indispensable.With the popularization of communication equipment,the demand of communication measuring instruments is increasing.In modern communication equipment measuring instruments,precise clock source is needed to ensure the accuracy of measurement data.Therefore,precise clock source has a broad application prospect.However,GPS signals are often only distributed outdoors,and there is almost no GPS signal indoors.A system that uses GPS to calibrate the clock is not suitable for working indoors.Based on this,this paper proposes a method to calibrate Voltage Controlled Crystal Oscillator(VCXO)based on the time interval measurement chip(TDC-GP22)and data-driven algorithm.TDC-GP22 is a local time interval measurement chip that can work in many occasions,whether indoor or outdoor.This method does not need to use GPS,but uses the TDCGP22 chip as the main tool for clock source frequency measurement.This method not only avoids the problem that the GPS calibration clock system can only work outdoors,but also has a good calibration effect.And,after MATLAB simulation,it can be found that it is feasible to calibrate VCXO using Data-driven methods.The content of this article is arranged as follows.First of all,this article introduce the basic knowledge of the crystal oscillator,including the physical structure of the crystal oscillator,the common parameters of the crystal oscillator,etc.,familiar with the working principle of the crystal oscillator.Secondly,this article analyze the existing crystal oscillator calibration Methods,analyze the advantages and disadvantages of various calibration methods,and the calibration effects they can achieve.Thirdly,this article proposes a crystal oscillator calibration scheme,base on data-driven method,using TDC to control the output frequency of the VCXO Calibration.Finally,this article introduce the process of complete hardware schematic design,PCB(Printed Circuit Board)design,data-driven algorithm design,and use MATLAB to complete the data-driven algorithm calibration VCXO simulation experiment.