Quality Factor

Quality Factor (Q Factor) is the ratio between the center frequency fand the half conductance bandwidth. It is used to measure the damping of a resonating device.


Conductance Plot

 It is calculated using the following formula:


Extracting Q factor requires conductance of the device. To do this, the review file (*.revinp) must contain the following code:

      histname electrode vq all      /* Volt/charge time histories 1 & 2

Once the input file is run, it creates a history file which is read into Review using the following code:

symb filename = INSERT_FILENAME_HERE /* Change filename as required
read f1 '$filename.flxhst'           /* Read time history

The conductance of the device can then be calculated using the following code:

file f2
wndo hann righ 1.
time pad $npad

type real
admt f1 2 f1 3

Then to get the value of f0, the #get command is used to extract the maximum peak value in the conductance curve. This value is then divided by 2 to get the values of  f & f 1 :

symb rpeak2 = $rpeak / 2
symb #get { incros } curvcros f2 1 $rpeak2 freq 2 $fmin $fmax

This gets the frequencies at the half conductance amplitude points which can then be used along with f0  to calculate Q:

symb Q = $rfreq / ( $freq2 - $freq1 )

Download: Q Factor Review Template