G-sensitivity is defined as a change in frequency resulting from an acceleration force applied to an oscillator. It is often expressed in terms of ppb/g. How does this affect performance? When an oscillator is used in an environment conducive to vibration, the frequency of the vibration will modulate the carrier frequency degrading the phase noise performance of the oscillator. This phenomenon is similar for both random and sine vibration and is also very deterministic meaning the magnitude of the induced phase noise degradation can be calculated if the g-sensitivity of the oscillator is known. John Vig has written an excellent tutorial on quartz crystals and resonator stabilities [1]. Please follow the link to an excerpt from John's tutorial which will provide a more detailed description of g-sensitivity and the equations for calculating the resulting phase noise in random and sine vibration environments.

John Vig Tutorial
[1] J.R. Vig, "Quartz Crystal Resonators and Oscillators – For Frequency Control and Timing Applications - A Tutorial", January 2004

	Product	Package Size (mm)	Frequency Range	Temp Stability –40 to 85°C	g-sensitivity	Shock	Vibration
MEMS	HT-MM900A	7.0 x 5.0 x 0.90 5.0 x 3.2 x 0.75 3.2 x 2.5 x 0.75 2.5 x 2.0 x 0.75 2.0 x 1.6 x 0.75	1 to 137 MHz	25ppm	0.1ppb/g
XO	PX-990	48.27 x 58.25 x 27	60 to 120 MHz	25ppm	0.5ppb/g
	PX-504	9.5 x 14.5 x 2.8	30 to 180 MHz	25ppm	0.3ppb/g
VCXO	VX-504	9.5 x 14.5 x 2.8	30 to 160 MHz	30ppm	0.3ppb/g
	VX-990	48.27 x 58.25 x 27	60 to 120 MHz	25ppm	0.5ppb/g
VCSO	VS-508	9 x 14 x 4.9	800 to 2900 MHz	20ppm	0.6ppb/g
TCXO	TX-707	5 x 7 x 2.8	8 to 52 MHz	1.0ppm	0.1ppb/g
	TX-705	7.0 x 5.0 x 1.1	16 to 50 MHz	1.0ppm	0.1ppb/g
	TX-550	11 x 9 x 3.7	8 to 150 MHz	1.0ppm	0.2ppb/g
	TX-321	23 x 18	5 to 50 MHz	1.0ppm	0.2ppb/g
OCXO	OX-080	37 x 37 x 13	8 to 15 MHz	30ppb	0.02ppb/g
	OX-043	52.07 x 52.07 x 26.67	8 to 15 MHz	30ppb	0.02ppb/g
	OX-046	52 x 52 x 20	50 to 250 MHz	200ppb	0.05ppb/g
	OX-407	14 x 20 x 11	10 to 50 MHz	100ppb	0.07ppb/g
	OX-405	13.21 x 20.83 x 10.16	80 to 120 MHz	700ppb	0.5ppb/g
	OX-990	48.27 x 58.25	60 to 120 MHz	200ppb	0.5 ppb/g

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