the Norton equivalent circuit of a current source

[Heidi]

Dear friends,

The schematic (p1) attached below is the implement of a current source from my textbook. The current i2 will be ten times as large as i1* if the nMOS M2 is operated in saturation.

* nMOS M1 parameters in PSPICE: lambda=0, W=100u, L=1u, Kp=0.01, Vto=1
M2: lambda=0, W=1000u, L=1u, Kp=0.01, Vto=1

I was trying to convert that current source into it's Norton equivalent circuit, so I connected its output terminal node Nd to ground (p2 below), finding the short-citcuited current to be 1.298A.
Next I removed the two DC voltage sources, making the circuit dead, and then inserted another voltage source (1 volt) between Nd and ground (p3), trying to find its Norton equivalent resistance by dividing this voltage by the resulting current.
It turned out that the equivalent resistance was pretty large (1V / 1pA = 1E12 ohms), but there was no current flowing through nMOS M1, even I replaced the 1V voltage source by a 100V voltage source. This makes me feel strange.

Could you please tell me if I correctly got the Norton equivalent circuit as the one in p4?

Thank you!

 

[Jugurtha]

Hello, Heidi

It might be me but no attachment appears on my side.

 

[steveB]

Wow, I just noticed that we didn't help you with this question. Maybe it's too late, but here is some feedback.

First, to answer your question ("Could you please tell me if I correctly got the Norton equivalent circuit as the one in p4?"), you didn't get the right answer.

Second, I've attached some notes that relate to this problem. This is a classic current mirror circuit.