.21.4 Mhz Crystal Oscillator Of The Microprocessor Temperature Compensation

Crystal oscillators are widely used in the devices of modern communications, navigation, measurement and other fields. However, many devices work in the environment which the temperature changes in a larger range, the change of temperature will cause the crystal oscillator's frequency shift. In this case, the crystal oscillator can not provide a stable clock frequency, which results in the abnormality of the device.According to the problem, this dissertation mainly carries out on the AT-cut crystal oscillator's low phase noise temperature compensation research. Based on the study of the frequency-temperature characteristics of AT-cut crystal oscillator and a variety of compensation techniques, this dissertation finally adopts a microprocessor temperature compensation method, which not only increases the temperature frequency stability of the 21.4MHz crystal oscillator but also reduces the phase noise. The content of the dissertation are as following.This dissertation studies the frequency-temperature characteristics as well as temperature compensation principle of the AT-cut crystal oscillator. Through the comparison of the traditional compensation methods, this dissertation brings forward the microprocessor temperature compensation method. The overall design is advanced, including VCXO oscillator circuit, the compensation network circuit and software design. At the same time, the principles and methods to reduce the phase noise are studied; the phase noise of 21.4MHz MTCXO is optimized. Then the sub-temperature compensation algorithm and interpolation algorithm are researched and selected. At last, the debugging is carried out through experiments and procedures optimization, and ultimately the design reaches the desired target.