Quartz Resonator & Oscillator Tutorial


	The f_ is used to gate a reciprocal counter that uses the fundamental mode frequency as the time base. The counter’s output is a number N₁ which varies with temperature. The microcomputer, in which f₁ vs. f_ calibration information specific to each resonator is stored, solves an equation and outputs a number N₂ which is used to correct for the variations of f₁ with temperature.
	Two correction methods have been used. In one, the SC-cut resonator is made to have a frequency that is slightly above the output frequency f_o at all temperatures, and pulse deletion is used to obtain an f_o that is stable over the temperature range. In the other method, the SC-cut resonator’s frequency is slightly below the output frequency f_o at all temperatures, and and a correction frequency (generated by means of a direct digital synthesizer) is added to obtain an f_o that is stable over the temperature range. The two methods are explained in more detail on the following pages.


	S. Schodowski, "Resonator Self-Temperature-Sensing Using a Dual-Harmonic-Mode Crystal Oscillator," Proc. 43rd Annual Symposium on Frequency Control, pp. 2-7, 1989, IEEE Catalog No. 89CH2690-6.

	R. Filler and J. Vig, "Resonators for the Microcomputer-Compensated Crystal Oscillator," Proc. 43rd Annual Symposium on Frequency Control, pp. 8-15, 1989, IEEE Catalog No. 89CH2690-6.