Agilent Technologies B1500A Self-Paced Training Manual page 104

To Use Auto Analysis Function
User Function
Analysis Function
In the Vth gmMax test definition, the user functions and analysis functions are defined to use the
auto analysis function. See the previous slide. The analysis function enables the line 1 for the Y1
data and displays the tangent line at the X-coordinate that takes the maximum gm value.
The following user function is used to calculate the gm value.
Gm = diff(Idrain, Vgate)
The following user function is used to get the maximum gm value.
gmMax = max(gm)
The following analysis function is used to get the Von value. The readout function @L1X gives
the X intercept value of the line 1.
Von = @L1X
The following analysis function is used to calculate the Vth value.
Vth = Von – (Vd*Polarity/2)
Where, Polarity is –1 for P-ch MOSFET or 1 for N-ch MOSFET.
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