# Trying to learn about netlists.

1. May 1, 2006

### Maxwell

I am trying to learn about transistor netlists and creating netlists for logic functions in SPICE.

For a MOS Inverter, I know:

Code (Text):

mosinverter
.option post
VG 2 0 DC PULSE 0 3 10NS 5NS 5NS 30NS 60NS
VDD 3 0 DC  3V
M1 1 2 3 3 pmos L=0.25U W=0.5U
M2 1 2 0 0 nmos L=0.25U W=.25U
.TRAN 10ps 150ns
.END

One of the big problems I'm having, I seemed to have not picked it up in class, is what this means:

Code (Text):

M1 1 2 3 3 pmos L=0.25U W=0.5U

Now, I know those are some sort of parameters, maybe the sizing (I'm referring to the "1 2 3 3")?

I assume M1 is the name of the single device we're creating. And I know what L and W are. But the 1 2 3 3 I'm pretty clueless about.

Also,

Code (Text):

VG 2 0 DC PULSE 0 3 10NS 5NS 5NS 30NS 60NS

Now, obviously Vg values are being determined here. Does the first 2 mean Vg = 2V? What's the zero after mean?

Code (Text):

VDD 3 0 DC  3V

I think here Vdd is just being defined as a 3V DC source. Since 3V is at the end, I assume the "3 0" does not mean 3V. What is the significance of the 3 there then?

Googling produces a lot of random results, so if someone could just fill me in on what the number and what each position corrosponds to, I may be able to live a little longer!

I get the idea that this stuff can be REALLY easy if you have a good reference source. Unfortunately, I don't. If you have a good site that just bluntly states what each position means, I would be VERY greatful!

Thank you.

2. May 1, 2006

### Corneo

M1 1 2 3 3
means connect a mosfet with the drain at 1, gate at 2, source at 3 and substrate at 3.

3. May 2, 2006

### Maxwell

Thanks, corneo.

I spent the day reading and asking people and I finally figured out what everything means. I can even design more complicated netlists. It is actually really simple once you get the basic idea down.