Spectre Transient Noise Simulation (Transistor sources, analytical behaviour)

Please can you provide the entire netlist (input.scs)? That way at least I have a chance to run some experiments.

By the way, sending me a friend request on the forums won't get your question answered more quickly - if it was urgent, you should contact customer support. I look at things in this forum in my spare time (it's not part of my job at Cadence to answer anything here), and this week I've had very little spare time...

Andrew

Hi Andrew! Thank you for your reply. I'm sorry for this inconvenience. I can contact the support as well. Please find below the netlist and model files link. Please let me know if anything else is needed. Thank you so much for your help. Regards, Priyesh

Model files: http://ptm.asu.edu/modelcard/PTM-MG/modelfiles/lstp/16nfet.pm     http://ptm.asu.edu/modelcard/PTM-MG/modelfiles/lstp/16pfet.pm  

//spectre netlist

simulator lang=spectre
global 0

include "local_model_file_path/nfet.pm"
include "local_model_file_path/pfet.pm"

//baseline CCI
M0 (Q PCH VDD VDD) pfet nfin=2 l=16n
M1 (Qb PCH VDD VDD) pfet nfin=2 l=16n
M2 (Q Qb VDD VDD) pfet nfin=2 l=16n
M3 (Qb Q VDD VDD) pfet nfin=2 l=16n
M4 (Q Qb netn 0) nfet nfin=1 l=16n
M5 (Qb Q netn 0) nfet nfin=1 l=16n
M6 (netn PCH 0 0) nfet nfin=1 l=16n

//uncomment M7 and M8 to connect these transistors to nodes Q and Qb with an idea of seeing more noise at Q and Qb
//M7 (Q 0 0 0) nfet nfin=50 l=16n
//M8 (Qb 0 0 0) nfet nfin=50 l=16n

V0 (VDD 0) vsource dc=0.85 type=dc
V1 (PCH 0) vsource type=pulse val0=0.85 val1=0 period=1n delay=0 rise=5p fall=5p width=495p

simulatorOptions options reltol=1e-3 vabstol=1e-6 iabstol=1e-12 temp=50.0 tnom=27 scalem=1.0 scale=1.0 gmin=1e-12 rforce=1 maxnotes=5 maxwarns=5 digits=5 cols=80 pivrel=1e-3 sensfile="../psf/sens.output" checklimitdest=psf

tran tran stop=1n errpreset=moderate method=trap noisefmax=200G noiseseed=5746 noisescale=2 write="spectre.ic" writefinal="spectre.fc" annotate=status maxiters=5

finalTimeOP info what=oppoint where=rawfile
modelParameter info what=models where=rawfile
element info what=inst where=rawfile
outputParameter info what=output where=rawfile
designParamVals info what=parameters where=rawfile
primitives info what=primitives where=rawfile
subckts info what=subckts where=rawfile

If you're going to contact customer support too, then I won't spend time on it here otherwise we'll be duplicating effort - that makes no sense.

Regards,

Andrew

If you're going to contact customer support too, then I won't spend time on it here otherwise we'll be duplicating effort - that makes no sense.

Regards,

Andrew

Hi Andrew, I am not contacting customer support since you wrote you can run some experiments. If you are unavailable then I will contact them. Since you are already in thread I feel it will be much faster to get help from you. Thank you. Regards, Priyesh

I spent a few minutes trying to figure out what's happening here. The circuit here seems rather unstable - try running for 10ns (with or without noise, and with or without the extra transistors). The extra transistors are off, and effectively are capacitors on the output - I don't think they contribute much to the noise but they do damp the output because of the capacitance (so actually the noise reduces). I did also try running pss and pnoise to check noise contributors but the circuit is behaving strangely when settled (if you can get it to converge) - so I wasn't entirely convinced that I could draw too many conclusions.

The device models seem to have default values for every noise parameter (compare with "spectre -h bsimcmg" which is the model used here).

Not really sure what you're expecting (and after all, these are fictional models so I'm not convinced anyone has taken a huge amount of care over them).

If you need more, please contact customer support - it's not obvious to me whether what you're expecting is realistic (and I don't have time to debug your circuit, however small it might be).

Andrew