An approach for temperature and frequency control of a crystal oscillator

This paper presents a new architecture for precise temperature control and stabilization of a crystal oscillator using microcontroller based proportional control and circuit compensation. By precisely controlling the temperature of the frequency-determining element of an oscillator, a very stable signal in the frequency domain is obtained. Additionally, holding the temperature constant at the crystal ldquoturning pointrdquo will minimize the effect on output frequency even when there is a small change in the temperature. The proposed architecture utilizes a temperature control circuit for stabilization, a digital voltage controlled circuit for precise tuning and an output buffer for load balancing and isolation. Main advantage of the proposed architecture is in its ability to precisely track frequency drift and stabilize the temperature variations of the crystal. Simulation results and practical implementations are detailed in the paper.