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Simulators >> Circuit Simulators >> minr in Spectre
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Message started by Sid on Jun 27^th, 2005, 11:17am

Title: minr in Spectre
Post by Sid on Jun 27^th, 2005, 11:17am

Hi,

I have very large MOSFETs in my DC-DC converter circuit. This results in the MOSFETs having a resistance less than 50 milli ohms. Now, Spectre does not consider these resistances since they are less than minr value. But I want it to simulate WITH these resistances included.

How do I change the minr parameter?

Thanks,
Sid

Title: Re: minr in Spectre
Post by Geoffrey_Coram on Jun 30^th, 2005, 5:24am

I believe you may have to set "minr=1e-3" in the model card for the large device(s). This could be a nuisance if you have lots of model cards. There is a simulator option

simOptions options minr=1e-3

but I think the local one (in the model card, which has a larger default) is applied first, without checking the global value.

Title: Re: minr in Spectre
Post by Ken Kundert on Jun 30^th, 2005, 7:51am

Using small values for parasitic resistors can cause convergence problems. If this occurs, you will need to loosen iabstol.

-Ken