# finding two drain currents

below I have the following problem along with the circuit's picture  My analysis is as follows:

for G and D open

\begin{equation} I_{D1}=I_{D2}\hspace{10mm}therefore\hspace{10mm}V_{ov1}=\:V_{ov2} \end{equation} \begin{equation} V_G+0.5=0.5-V_G\hspace{5mm}therefore\hspace{5mm}V_G=0 \end{equation} using the this equation: \begin{equation} I_D=\frac{1}{2}k_nV_{ov}^2 \end{equation} we see that: \begin{equation} I_{D1}=I_{D2} = 0.125mA \end{equation}

My problem is that my analytical results don't agree with my simulation results below

We see from the simulation that V_G = 0.4375 which is not zero according to my analytical work. Also, the current I_D = 0.000439453 which is not 0.125mA according to my calculations. Can somebody please tell me what am I doing wrong. Thanks in advance for all the help.

• Your analysis seems correct; I think the simulation must be wrong. Check all the settings in it. Jun 12, 2018 at 4:21
• I checked it too many times already. Can't find what is wrong with it. Also, I have used it as it's for other problems and it was giving me accurate answers Jun 12, 2018 at 4:35
• I repeated your by-hand analysis and got the same result--both transistors in saturation etc. So I am at a loss; I hope someone else comments. Jun 12, 2018 at 15:39
• One question, why does W=2 in the simulation? Jun 12, 2018 at 15:40
• Just for convenience purpose because total k_n =2mA/V^2 Jun 12, 2018 at 15:43