How to simulate opamp offset by monte-carlo?

[jacobliu]

Hi,

I'm trying to use hspice simulate opamp offset voltage by monte-carlo.
But i don't know how to set the value.
There are many offset parameter in BSIM3 mos spice model.
such as

LINT Length offset fitting parameter from I-V without bias
WINT Width offset fitting parameter from I-V without bias
WL Coefficient of length dependence for width offset
WLN Power of length dependence for width offset
WW Coefficient of width dependence for width offset
WWN Power of width dependence for width offset
LL Coefficient of length dependence for length offset
LLN Power of length dependence for length offset
LW Coefficient of width dependence for length offset
LWN Power of width dependence for length offset
LWL Coefficient of length and width cross term for length offset
XL The masking and etching effects of channel length
XW The masking and etching effects of channel width

please make an example of opamp offset voltage by monte-carlo in hspice.

regards,

 

[shaq]

Try .dcmatch in Hspice 2006 above

 

[alias0823]

In spice, MOS parameter "delvto" can be used to do op offset simulation.
You can reference Razavi's book chapter13 to estimate your mos Vth offset, then apply it to delvto at every MOS. Monte-Carlo simulation then can be done.

It is a easy way for me to roughly determine your MOS size in OP for acceptable offset.

 

[joe_chen]

pl explain it in more detail