a basic question about hspice netlist

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lyrix

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in hspice netlist for a mos
M0 net1 net2 net3 net4 model L W AS AD PS PD M

Parameter AD AS PD PS are the total aera/perimeter of drain/source
or AD*M AS*M PD*M PS*M are total value??
 

It's just for a single finger, mag factor is not accounted. Also, note that perimeter numbers do not include the side of gate.
 

The perimeter parameters DO include the sides of the gates. This is stated in the Star-Hspice Manual:
PD Perimeter of the drain junction, including the channel edge.
 

Hughes said:
The perimeter parameters DO include the sides of the gates. This is stated in the Star-Hspice Manual:
PD Perimeter of the drain junction, including the channel edge.
Click to expand...

Thanks Hughes, my bad.
 

I remembered when I was reading some documents, it is stated that the channel edge should not be included.

It used to make sense to me. Because I do not want to calculate the side-wall cap for this edge since the edge will merge into the channel.

However, the junction is deeper than the channel, maybe that is the reason we can not ignore it.
 

When M is not equal to 1, these parameters depend on the layout topology. In Hspice, I remember at least there is one parameter to control the layout, which might be GEO (not quite sure now).
 

GEO can control sharing the drain and source with other devices.

Still, I do not recommend let hspice calculate the geometric parameters. For critcal devices, we should use subckt to accurately calculate the parameters.
 

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