Temperature Compensated Crystal Oscillator (TCXO) Design Aids: Frequency-Temperature Resonator Characteristics as Shifted by Series Capacitors

Resonators for TCXO application are required to have accurately- characterized frequency-temperature f-T curves and equivalent network parameters. This report describes how the circuit parameters, critical resonator frequencies, and temperature coefficients depend on material constants of the crystal and geometrical factors. These constants are tabulated for AT- and SC- cut quartz. It further explains the observed f-T curve shift between resonator operation with and without series load capacitors. Simple relations are given for treating this effect, along with charts and other design aids. These are used in a practical example involving an AT-cut resonator for a typical TCXO application.