Hi,
I noticed the description for device 'nmoscap' is NMOS in N-Well varactor and there are two fields:
CapValue_(F): variable_a F
CapValue@0V_(F): variable_b F
It appears clear that variable_b means under the bias voltage (Vgs; S and D are short connected), the Capacitance(Cgs) is this variable_b value. What does variable_a mean? Is it any voltage else will result in a variable_a capacitance or the maximum capacitance under the maximum voltage for a certain W/L it can present? I believe the latter case is true but not quite sure because the maximum is what? Vdd?. Vdd is different in different technology, how to determine which exact capacitance will be for different Vdd?
Also I have searched technology documentation and other related pdf files in the PDK, not much saying on nmoscap. There is one mos varactor, but with size scaling from 0.4u-3.2u for W and 0.4u-2u for L instead of the device that I am caring about which is from 50u to 50um for both W and L. It looks I cannot find any documentation of this device 'nmoscap'. Any idea?
Thanks,
Alex