3

I have a table of values given to me which contains drain current Id (in μA) and gate voltage (in volts) calculated in the saturation region for a thin film transistor.

I need to find the threshold voltage by drawing a graph. I used Desmos to draw the graph based on the given values.

I know that threshold voltage is defined as the gate voltage at which a device starts to conduct, but I'm confused as to which gate voltage I should consider.

enter image description here

SamGibson
  • 17,231
  • 5
  • 37
  • 58
blackblade
  • 378
  • 1
  • 8
  • Are you sure that X axis is in volts? – John D Oct 28 '22 at 19:32
  • @JohnD Yes, it is in volts but maybe a printing mistake and actually it is in millivolts. But still, which point to consider? – blackblade Oct 29 '22 at 09:58
  • "*I know that threshold voltage is defined as the gate voltage at which a device starts to conduct,*" If starting of conduction is where the \$I_d\$ first exceeds 0 \$\mu\$A then where is that on your graph? – Transistor Oct 29 '22 at 11:07

2 Answers2

0

You are supposed to take square root of drain current and then plot it. Then extend the line to x-axis to get the intercept which is the threshold voltage.

blackblade
  • 378
  • 1
  • 8
-1

From wikipedia:

The threshold voltage, commonly abbreviated as Vth or VGS(th), of a field-effect transistor (FET) is the minimum gate-to-source voltage (VGS) that is needed to create a conducting path between the source and drain terminals.

RemyHx
  • 736
  • 2
  • 9