Channel Length Modulation (lambda): SPICE Problem

[srivatsan]

channel length modulation lambda

I am trying to calculate the channel length modulation from the output graph after simulation in spice. I view the output in nutmeg.

I am trying to convert the output (which is in binary) to ascii. So that I can import on to MATLAB or whatever and try to understand whether the design is working okay or not. Of course this method will have error but it is good enough for that W/L and VDS rnage at a VGS value.

Now I am not able to convert the binary to ascii. I understand that it would be due to compressed-binary-encoding of the output voltages as it helps in having compressed output files.

Has anyone tried to do what I am trying now?? If so, then reply.
Thanks in Advance.

Srivatsan

 

[Fom]

channel length modulation

What simulation software do you use? Spice is just common name.
Why you cannot print out your results to text file?

 

[Hughes]

channel length modulation hspice

I don't use Nutmeg for spice-level simulation. But I think it should support .print statement. Print out the results and you will get ascii data.

 

[srivatsan]

ngnutmeg set filetype=ascii

Well, I am using specifically, ngspice for simulation of circuit and ngnutmeg for viewing the output.
Now, when I used print command in ngnutmeg (print i(V4)), it worked (I saw the actual data interms of ascii).
Now I dont know how to get it on to a file. (Note I am in UNIX and therefore I dont mind what is the file and its extension. )
When I did "write i(V4) > data", it dumped me a segmentation core. So I did not understand about "writing" i(V4) values on to a file as ascii characters. If you can help me inthis it would be great...
thanks.
srivatsan

 

[srivatsan]

calculate lambda spice

Well, I found how to save the nodal voltage or current values as a file in UNIX environment and if you are using nutmeg.

log on to nutmeg
load the output file
follow the commands written below:
1. set filetype = ascii
2. write <filename> i(V4) v(5)
3. quit

Now you are outside nutmeg. you can access the filename file and work on it.
Thanks to all who answered..
srivatsan

 

[GusTheCat]

channel length modulation hspice parameter

Well, I may be foolhardy... or brutal, as they call it. I will go ahead and grab screen shot, store it as bmp or jpeg, then use Matlab to read it in, then search for the location where the color is the plot, then I get coordinate information.

Once I was battling with getting publishing quality plots, and this is the way I used.

 

[srivatsan]

modulator am +spice

hi GustheCat,
I tired that first.. of course who wants to find out how to save files in this way or that way.... takes time.. but i had no options as i required to get the channel length modulation little fast, repeatable, accurate. it is because when designing analog circuits, lambda would be more accurate when you actually plot the whole I-V for that vgs and ramp with vds. it really helps.... as it avoids big equations which uses PCLM model parameter in bsim3v3...
srivats

 

[sudheerkm]

attachment didnot come

Added after 26 minutes:

ngspice -b simple.sp -o simple.out -r simple.raw

i am attaching mfile to read .raw file

Added after 2 minutes:

mfile does not come

 

[sudheerkm]

if u use octave

u can plot the output in octave (is a gnu alternative for matlab all the matlab commands more or less works there)

i am attaching octave spice

see this link
http://ngspice.sourceforge.net/octavespice.html