What is Absolute Pulling Range?

Crystal Oscillators 
What does absolute pulling range for a VCXO mean? What is the difference Between Absolute Pulling Range and Total Pulling Range?
Tagsvcxo
1 Answer
Can you answer this question?
318 people have viewed this question

Editorial Team - everything RF

Feb 8, 2018

A VCXO is a Crystal Oscillator that varies output frequency based on an applied control voltage. The maximum variation in VCXO's output frequency over changes in control voltage under a constant supply voltage and temperature - specified in ppm - is called Pullability or Total Pulling Range. 

The Absolute Pulling Range is the minimum guaranteed deviation of the VCXO from the center frequency, when the control voltage is set to the maximum and minimum values. It is guaranteed over manufacturing tolerances, supply voltage, operating temperature and aging. 

Absolute Pulling Range can be calculated after subtracting the errors (errors due to temperature + aging + power supply + load) from the Total Pulling Range. It is also called as Usable Pullability.
In the above example, the total pull range is 160, whereas the absolute pulling range is 100

What is the difference Between Absolute Pulling Range and Total Pulling Range?


In the example given, we need to find out which VCXO can be used in a PLL that needs to track a ±50ppm reference. 

Initially it seems like as VCXO A has more pullability, but when we take into account all the errors, we find out that VCXO B actually has more pullability.  And VCXO B is suitable to be used in the PLL to track ±50ppm. 

APR is also called "Usable Pullability".