Frequency stability or temperature coefficient, by its own definition, has two elements, frequency change (deviation) and temperature range. Frequency change is expressed as positive and negative deviation from the nominal design frequency in Hz., percent or PPM. The temperature range, also known as the Operating Temperature Range - OTR. is delineated by stating the upper and lower limits. Three examples of the same stability specification for a crystal are as follows:
+/- 100 Hz. -40/+85 deg. C*
+/- .001% -40/+85 deg. C*
+/- 10 PPM -40/+85 deg. C*
*As referenced to the frequency at 25 deg. C. Calibration tolerance, aging and temperature stability are the components of ABSOLUTE STABILITY and are additive. It is important to understand each component's limitation and the effect it has on manufacturability and cost/price.
VERY HIGH PRECISION: +/- 2 PPM (cost driver)
HIGH PRECISION: +/- 5 PPM (cost driver)
PRECISION: +/- 10 PPM (moderate cost driver)
SEMI-PRECISION: +/- 20 PPM
LOW PRECISION: +/- 30 PPM
NON-PRECISION: +/- 100 PPM
GENERALIZED TEMPERATURE RANGES:
FULL MILITARY: -55/+125 deg. C (cost driver)
MILITARY: -55/+105 deg. C
SECONDARY MILITARY: -40/+ 90 deg. C
INDUSTRIAL: -40/+ 85 deg. C
COMMERCIAL: -20/+ 70 deg. C
OCXO (typical) +75/+ 85 deg. C
Note that deviation and temperature range can be mutually exclusive. There are limitations as a result of the Laws of Physics. Narrow frequency deviations are typically not possible over very wide temperature changes. Reducing the frequency deviation and/or widening the operating temperature range are major cost drivers in quartz crystal resonators.
Even if there appears to be a Cut-Angle that will produce a desired temperature coefficient, the limited tolerance associated with the Cut-Angle will make manufacture of the resonator impractical due to the low yield of temperature stability compliant resonators.
[Home] [Product Search] [Find a Representative] [Technical Information] [Contact Us] [About Us]
Copyright 2003 Anderson Electronics, LLC