I'm simply trying to find Vt and W/L for a given practice exam problem shown below:
Initially, I was trying to use the equation as shown in line 1 of the solution to develop 2 equations with 2 unknowns and solve for each, but there appears to be a much faster way to arrive at the solution which I'm having trouble understanding. Specifically, I don't understand line 2 of the solution.
What is the logic behind taking the ratio of Id (0.225mA/0.1mA = 2.25)?
The book defines VGT as Vgs-Vt, I don't understand which numbers/logic is used to determine Vgt1/Vgt2 = 1.5. I suspect VGT is not equal to Vgt (lower case), but can't find a formal definition to support my suspicion.
And Finally, how is Vt = 0.6V? The most I can rationalize is that 1.5/2.25 = 0.66667, but doesn't seem right.
I appreciate any help. Thank you.
*This is a practice exam, not hw