The Study, Based On The New Temperature Control System For The Oven-controlled Crystal Oscillator

As the development of electronic technology, high-stability crystal oscillator is being used more and more widely. Especially, the oven controlled crystal oscillators (OCXO), which is 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. It is the "heart" of these equipments, because it works as the reference frequency source and the critical part of them. This thesis analyzes a new temperature control method, and researchs the performance of OCXO based on the new temperature control circuit.This thesis is aimed to increase frequency stability of OCXO and improve start-up charateristic. First, the influence of quartz resonator's characteristic of electrical, frequency-temperature etc on crystal oscillator is analyzed.By that we determine the necessity of temperature control. We discuss component part and technical target of OCXO.According to the principle of oscillator circuit, we design a typical circuit. After that, we emphasize on the design of temperature control circuit. A new temperature control method based on PID control is analyzed, compared to traditional circuit, the integral and differential part is added to the new temperature control circuit. Based on a temperature control IC ADN8830, it can simplify the exterior circuit of control system for the high integration of ADN8830 and increase the reliability of device with lower power consumption, high stability and smaller size. We analyze the dominating parts of the circuit including temperature measurement circuit, PID controller and power output circuit, obtain the whole schematic diagram and PCB. After comparing to traditional circuit, we find the new control circuit has some good performance such as fast warming-up, high temperature stability and high thermal efficiency. Then, we design two structures of the oven after simply analyzing the temperature field of the oven and the effect of the thermistor's position on performance. At last, we test and analyze the results of OCXO. The experiment shows the frequency stability can reach 10^-8 based the new temperature control circuit and single oven structure.