confusion about c_comp

Hi,
 
I am a bit confused about c_comp. C_comp is the silicon die capacitance,
which includes the parasitic capacitance of the buffer, the bond wire and
the die pad capacitance. When the Spice simulations are run to generate the
IBIS data, the effects of the c_comp parameter should already be included
(since you can't take away the parasitic capacitance of the circuit). So
when the [c_comp] keyword is specified, isn't the effect of c_comp
double-counted?
 
For example, when I generated my IBIS model, I estimated the value of the
bond wire and die pad capacitance, and added that as an explicit capacitance
to the buffer output before using Spice to extract data. Then I estimated
the value of parasitic capacitance of the buffer circuit (as described by
Arpad Muranyi). The total [c_comp] value is the sum of bond wire and die
pad capacitance, and the parasitic capacitance of the circuit. Is this
approach correct?
 
I would really appreciate any feedback.
 
Thanks very much,
Betty Luk

 
Received on Wed Dec 20 10:35:40 2000