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Modeling >> Semiconductor Devices >> vbic HBT rth & cth conversion SpectreRF to HSPICE
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Message started by imtired on Nov 12^th, 2007, 12:05pm

Title: vbic HBT rth & cth conversion SpectreRF to HSPICE
Post by imtired on Nov 12^th, 2007, 12:05pm

HI all,

I am in need of some help converting VBIC HBT parameter units for the self-heating thermal resistance and capacitance "rth" and "cth" from SpectreRF to HSPICE. I found that the untis in SPectreRF for these two parameters are ohms and Farads, respectively, but in HSPICE the units are in K/W and J/K. Does anyone know how to do this?

Thanks,
RU

Title: Re: vbic HBT rth & cth conversion SpectreRF to HSP
Post by Geoffrey_Coram on Nov 12^th, 2007, 1:04pm

I think the HSpice units are correct, and the Spectre folks are perhaps a little sloppy. You shouldn't need any conversion.

"rth" is implemented as a resistor (in terms of its matrix stamp), but the "current" that flows through it is heat (power) and the "voltage" across it is really temperature (in Kelvin).

Title: Re: vbic HBT rth & cth conversion SpectreRF to HSP
Post by imtired on Nov 12^th, 2007, 6:24pm

So it was just a matter of describing the units in different domains, HSpice in thermal domain, and SpectreRF in the electrical domain.
That makes more sense to me now, and so I don't need to do any conversion of the parameters Rth and Cth.
Thanks Geoffrey.