Frequency-temperature-load capacitance behavior of resonators for TCXO application

The effective frequency-temperature (F-T) curve of a crystal resonator operated with series load capacitance differs from that of the crystal alone. Since the principal method of compensating for the crystal F-T behavior in a temperature compensated crystal oscillator (TCXO) employs series varactors and a temperature sensitive compensation network, it is of major importance to be able to understand and deal with this effect in the design of TCXOs. The necessary formulas and discussion are given in this work.