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Modeling >> Semiconductor Devices >> questions about BSIM4 gate resistance model
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Message started by sapphire on Aug 13^th, 2009, 7:56pm

Title: questions about BSIM4 gate resistance model
Post by sapphire on Aug 13^th, 2009, 7:56pm

Hi there,

It provides four options to model gate resistance. The 3rd and 4th options consider channel NQS effect, but I am not sure about what's exactly the difference? Therefore, I don't know how to choose between these two.

Actually, I am doing a simple noise analysis on a common-source amplifier. These two options give much difference noise voltage from gate resistance as a whole.

Thanks

edward

Title: Re: questions about BSIM4 gate resistance model
Post by Geoffrey_Coram on Aug 17^th, 2009, 6:16am

rgatemod=2 and 3 have two resistances, a constant "electrode" resistance (for the contact) and a variable resistance. rgatemod=2 computes the effective series resistance and adds a single extra node to the circuit matrix. rgatemod=3 add two extra nodes, keeps the two resistors separate, and also connects the overlap capacitances (CGSO, CGDO, and I think CGBO) to the point in the middle of the two resistors. I believe the argument is this is more accurate, but perhaps not worth the extra matrix row (which can make for a large matrix in big circuits).