SPICECAD has many built-in features concerning MOS transistors.
SPICECAD has a built-in formula which calculates and netlists these parameters.
The formulae are:
AD=AS=gate_width * diff_width
PD=PS=gate_width*2 + 2*diff_width
NRS=NRD= gate_width/cont_spacing
diff_width and cont_spacing can be defind in file 'setup.spi'.
Not yet implemented, but soon :
If you have folded transistors, you can specify the folding factor 'm',
which is a MOS property. By default, 'm' equals one, which means that the
transistor is made of a single gate.
Setting m=2 means the transistor is made of two gates, and so on.
So,
AD=AS=gate_width * diff_width / m
PD=PS=gate_width*2 + 2*diff_width / m
NRS=NRD= gate_width/cont_spacing / m
Okay, these formulas are not exact, but better than nothing. If you want better ones, tell us. It is easy to change that.
To locally override the value of the global variable
'multiply_mos_w_with_m',
you can use the following syntax at the MOS transistor property:
'm 4|'
means that m is set to 4 and that 4 transistors are written into
the netlist regardless of the value of 'multiply_mos_w_with_m'.
'm 4-'
means that the transistor width will be multiplied by 4 and that
only one transistor is written into the netlist regardless of the value
of 'multiply_mos_w_with_m'.