2-7
Temperature
Sensor
Compensation
Network or
Computer
XO
· Temperature Compensated (TCXO)
-450C
+1 ppm
-1 ppm
+1000C
T
Oven
control
XO
Temperature
Sensor
Oven
· Oven Controlled (OCXO)
-450C
+1 x 10-8
-1 x 10-8
+1000C
T
Voltage
Tune
Output
· Crystal Oscillator (XO)
-450C
-10 ppm
+10 ppm
250C
T
+1000C
Crystal Oscillator Categories
   A wide temperature range XO has a typical f vs. T stability of ~10 to 50 ppm.  A TCXO can reduce that to ~1 ppm.  An OCXO can reduce that stability to 1 x 10-8 or better (but at the cost of much higher power consumption).  High-end (SC-cut) OCXOs can stay within 1 x 10-10 over a wide temperature range.