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two puzzles about the "M" of mos model in hspice

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nige

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hi, everybody, I'm doing a post-layout simulation using the lpe hspice netlist and two troubles puzzled me now. I hope somebody can help me.

*the first puzzle: as we all know, the foundry usually has a limition of "w" value about the mosfet, so when we design a big mosfet, we used a legal "w" value and argument "M". but I found in the lpe hspice netlist, all the big mosfet directly have a width value of "w times M" instead of "w" and "M".

for example:
pre layout nelist: M1 2 3 4 vss model L=0.24u W=80u M=9
post layout netlist: M1 2 3 4 vss model L=0.24u W=720u

can the second type of netlist be simulated post-layout directly?

*the second puzzle: the post-layout netlist must have some values of "AD","AS","PD" and "PS", so if we used the argument "M" at the same time, is the effect of "AD","AS","PD" and "PS" multipled ?

the two puzzle refer to almost the same question, I guess the netlist as
"M1 2 3 4 vss model L=0.24u W=720u"
can't be simulated directly, so we should change the netlist into the form of
"M1 2 3 4 vss model L=0.24u W=80u M=9" and we must add the parasitical value of "AD","AS","PD" and "PS" into it manually. In this conditiono,how about the the effect of "AD","AS","PD" and "PS"? I don't think the value of "AD","AS","PD" and "PS" can be divided by "M".

thank you in advance.
 

check your rule file.
there is a switch about merge or not the mos size
 

Re: two puzzles about the "M" of mos model in hspi

In the second question the answer is yes, AS AD etc are multiplied. Not exaclty like in real life where the transistors share the drain or source.
 

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