Quality Factor

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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. 

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Conductance Plot

 It is calculated using the following formula:

eqn.PNG

Extracting Q factor requires conductance of the device. To do this, the input file must contain the following code:

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

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:

freq
file f2
wndo hann righ 1.
time pad $npad

type real
admt f1 2 f1 3
end

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& f1 :

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 our Review template to calculate Q factor here
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