monte carlo result on std dev and sigma

Hello all,

Still I have some doubt about the sigma and std in Monte Carlo analysis in IC5 and MMSIM 12. I realised that the Monte Carlo analysis uses two files, which are:
<MOSFETname>_mc_statistical_m.mdl.scs and <MOSFETname>_mc_statistical_p.mdl.scs.

I checked the file '<MOSFETname>_mc_statistical_m.mdl.scs', and apparently it has to do with mismatch analysis of the  below I put content of the file. What does std=1/1 mean?

simulator lang=spectre insensitive=yes
parameters mc_n_<MOSFETname>_vth0_ma = 0
parameters mc_n_<MOSFETname>_u0_ma = 0
parameters mc_p_<MOSFETname>_vth0_ma = 0
parameters mc_p_<MOSFETname>_u0_ma = 0
//
statistics {
mismatch {
vary mc_n_<MOSFETname>_vth0_ma dist=gauss std=1/1
vary mc_n_<MOSFETname>_u0_ma dist=gauss std=1/1
vary mc_p_<MOSFETname>_vth0_ma dist=gauss std=1/1
vary mc_p_<MOSFETname>_u0_ma dist=gauss std=1/1
 }
}

-----------------------------------------

There is another file called '<MOSFETname>_mc_statistical_p.mdl.scs' and as far as I understand it has to do with process analysis in Monte Carlo, and below is the content.

simulator lang=spectre insensitive=yes
//
parameters mc_n_<MOSFETname>_tox_np = 0
parameters mc_n_<MOSFETname>_cj = 0
parameters mc_n_<MOSFETname>_cjsw = 0
parameters mc_n_<MOSFETname>_cjswg = 0
parameters mc_p_<MOSFETname>_cj = 0
...
//
parameters dtox_n_<MOSFETname> = 2.7300e-09 * (0.0300 / 3 * mc_n_<MOSFETname>_tox_np)
parameters dvth0_n_<MOSFETname> = (2.40000e-02 / 3) * mc_n_<MOSFETname>_vth0
parameters du0_n_<MOSFETname> = (1.50000e-04 / 3) * mc_n_<MOSFETname>_u0
parameters dvsat_n_<MOSFETname> = (0.00000e+00 / 3) * mc_n_<MOSFETname>_vsat
parameters dwint_n_<MOSFETname> = (1.00000e-08 / 3) * mc_n_<MOSFETname>_wint
parameters dlint_n_<MOSFETname> = (1.00000e-09 / 3) * mc_n_<MOSFETname>_lint
...
//
statistics {
process {
vary mc_n_<MOSFETname>_tox_np dist=gauss std=sigma/3
vary mc_n_<MOSFETname>_cj dist=gauss std=sigma/3
vary mc_n_<MOSFETname>_cjsw dist=gauss std=sigma/3
vary mc_n_<MOSFETname>_cjswg dist=gauss std=sigma/3
vary mc_p_<MOSFETname>_cj dist=gauss std=sigma/3
vary mc_p_<MOSFETname>_cjsw dist=gauss std=sigma/3
...
}

To me sigma is a parameter which is only required for mismatch calculations of Monte Carlo analysis, am I right?


For my circuit there is not much of variation in Process Only, but there are a lot of disappointing variation in Mismatch Only. I thought that std is in percent, so I changed it to std=0.1 and the Mismatch variations are relatively better. Can anyone tell me that my interpretation is true or not? Please!

Hello all,

Still I have some doubt about the sigma and std in Monte Carlo analysis in IC5 and MMSIM 12. I realised that the Monte Carlo analysis uses two files, which are:
<MOSFETname>_mc_statistical_m.mdl.scs and <MOSFETname>_mc_statistical_p.mdl.scs.

I checked the file '<MOSFETname>_mc_statistical_m.mdl.scs', and apparently it has to do with mismatch analysis of the  below I put content of the file. What does std=1/1 mean?

simulator lang=spectre insensitive=yes
parameters mc_n_<MOSFETname>_vth0_ma = 0
parameters mc_n_<MOSFETname>_u0_ma = 0
parameters mc_p_<MOSFETname>_vth0_ma = 0
parameters mc_p_<MOSFETname>_u0_ma = 0
//
statistics {
mismatch {
vary mc_n_<MOSFETname>_vth0_ma dist=gauss std=1/1
vary mc_n_<MOSFETname>_u0_ma dist=gauss std=1/1
vary mc_p_<MOSFETname>_vth0_ma dist=gauss std=1/1
vary mc_p_<MOSFETname>_u0_ma dist=gauss std=1/1
 }
}

-----------------------------------------

There is another file called '<MOSFETname>_mc_statistical_p.mdl.scs' and as far as I understand it has to do with process analysis in Monte Carlo, and below is the content.

simulator lang=spectre insensitive=yes
//
parameters mc_n_<MOSFETname>_tox_np = 0
parameters mc_n_<MOSFETname>_cj = 0
parameters mc_n_<MOSFETname>_cjsw = 0
parameters mc_n_<MOSFETname>_cjswg = 0
parameters mc_p_<MOSFETname>_cj = 0
...
//
parameters dtox_n_<MOSFETname> = 2.7300e-09 * (0.0300 / 3 * mc_n_<MOSFETname>_tox_np)
parameters dvth0_n_<MOSFETname> = (2.40000e-02 / 3) * mc_n_<MOSFETname>_vth0
parameters du0_n_<MOSFETname> = (1.50000e-04 / 3) * mc_n_<MOSFETname>_u0
parameters dvsat_n_<MOSFETname> = (0.00000e+00 / 3) * mc_n_<MOSFETname>_vsat
parameters dwint_n_<MOSFETname> = (1.00000e-08 / 3) * mc_n_<MOSFETname>_wint
parameters dlint_n_<MOSFETname> = (1.00000e-09 / 3) * mc_n_<MOSFETname>_lint
...
//
statistics {
process {
vary mc_n_<MOSFETname>_tox_np dist=gauss std=sigma/3
vary mc_n_<MOSFETname>_cj dist=gauss std=sigma/3
vary mc_n_<MOSFETname>_cjsw dist=gauss std=sigma/3
vary mc_n_<MOSFETname>_cjswg dist=gauss std=sigma/3
vary mc_p_<MOSFETname>_cj dist=gauss std=sigma/3
vary mc_p_<MOSFETname>_cjsw dist=gauss std=sigma/3
...
}

To me sigma is a parameter which is only required for mismatch calculations of Monte Carlo analysis, am I right?


For my circuit there is not much of variation in Process Only, but there are a lot of disappointing variation in Mismatch Only. I thought that std is in percent, so I changed it to std=0.1 and the Mismatch variations are relatively better. Can anyone tell me that my interpretation is true or not? Please!