it is said that hspice will calculate the junction capcitance automatically with w, L only. for the warning, seems it won't calculate the Cj correctly assuming Pd=0?
or my hspice is outdated?
thanks chunlee, you mean it is normal to get the warning like this? i was trying to extract a hspice netlist from cadence tool, it did have ps pd value. Compare the capacitance, there are some differences. I just thought the hspice should generate some pd value, which should depend on the mosfet size(w,L).---it is just the drain perimeter.
thanks again
hspice has default value for pd ps ad as. if i don't forgot, the default value is 0. I don't use cadence before. so i don't know cadence will generate pd and ps automatically or not. But again, pd ps ad as is depend the layout u draw.
But u can use following formula to estimate the value of pd ps ad as. formula was given by somebody in this forum.
AD = AS = 2.5*Lmin*W
PD = PS = 5*Lmin + W or 5*Lmin