A novel voltage controlled temperature compensated crystal oscillator for eliminating the trim effect

A novel scheme of voltage controlled temperature compensated crystal oscillator (VCTCXO) which could realize frequency adjustment and temperature compensation simultaneously is presented. The scheme is based on the binary function V = F(T, f_t) which could be obtained from the temperature experiments, where f_t is the target output frequency (controlled and adjusted by external control voltage); T is the ambient temperature and V is the compensating voltage. Through extending the two-dimensional temperature-frequency characteristics curve to three-dimensional surface and using a microcontroller to works out compensating voltages according to the above binary function, this new approach provides the possibility for eliminating the adverse influence of trim effect on traditional temperature compensated crystal oscillators (TCXOs).