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Hspice mos capacitance output & parameters in mosfet output templates

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cl254

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Dear All,

If we do a .OP in HSPICE, for a transistor we can see at the end of the list there are cdtot/cgtot/cstot/cbtot/cgs/cgd. For the transconductance gm, it can be easily called by LX7 (GMO, DC gate transconductance). How about the corresponding MOS parameters for each of cdtot/cgtot/cstot/cbtot/cgs/cgd?

As far as I know, cdtot= cgd + cdb, if there are corresponding parameters for cgd and cdb, that's good as well.

Thank you!
 

If you want to measure the total output capacitance, bias the transistor to the required OP, connect an ac unit current source (1A) between output & GND, run an ac simulation and plot the ac output voltage vs. frequency - log-log plot at best. Voltage means Ohms, because you divide by 1A. From any point of the falling branch do the math.

If the plot shows a horizontal branch, subtract this DC resistance part - quadratically, of course.
 

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