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So I am given the IV characteristic plot along with the resistive load circuit which looks like: enter image description here

The load is a 25k resistor. I want to understand how to actually do the problem which is why i didn't provide the IV characteristic plot. So based on the plot, where i have 5 Vgs values, and the circuit above, how do I draw a VTC plot? I don't even know where to begin and I've scoured google for a while now and I've only found questions without solutions.

Can someone give me a quick starter on how I should go about this?

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The IV characteristic of the switch, I take it? –  Chintalagiri Shashank Mar 1 '13 at 2:44
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up vote 1 down vote accepted

The vtc plot would plot vout vs vin. I've seen vin on vert axis, and vout on horiz, but could be either way. You say you have iv plot for the transistor, 5 curves for 5 values of vgs. The vgs values are your vin values, so now you want vout values. To find the vout values, plot an iv line for the resistor on your iv plot, and see where it intersects each of the iv lines. Ie, the same current flowsin the fet as in load resistor, so where the lines describing the possible iv combos at the connection between the two components cross, that's the combo that will occur.

The only wrinkle is that the line you plot for the resistor uses NOT the voltage across the resistor, but the voltage at the junction of r and the transistor. So, supposing a v+ of 10v, and 25kohm, you would plot a line from (0v,10/25 mA) to (10v, 0 mA). These correspond respectively to what the resistor will do with the transistor so on that its shorting to ground, and the transistor fully off.

Hope that helps.

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