Study On Oven Controlled Crystal Oscillator Of High Stability And Small Size

Oven controlled crystal oscillators (OCXO) as a highest frequency stability among crystal oscillator is widely used in communications equipment, measuring instruments, navigation, radar, mobile communication, programmed telephone, audio-visual equipment etc. This thesis is aimed to research and design a novel OCXO with small size and high stability based on single oven structure through delicate designing of the oscillating circuit, temperature control circuit and the oven structure. The main content of the thesis is as follows: The influence of quartz resonator's characteristic of electrical, frequency –temperature, ageing etc have on crystal oscillator has been discussed. By that we choose the high quality quartz resonator for OCXO. According to the basic theory of crystal oscillator circuit high frequency stability oscillating circuit is designed. Two temperature control methods are discussed and compared here. One way is adopt the temperature control integrate chip AND8830, its work is mainly the design of hardware circuit. With its high integrate OCXO has high stability, high reliability and small size. another way is using the Atmega8 microprocessor software program to realize PID control and PWM output, in order to improve the performance the intelligent integral apart and incompletion differential coefficient are introduced based the classical PID. Temperature field within oven structure is researched, and high performance oven structure is designed from both a theoretic viewpoint and actual experimentation.