MIM Parasitic Capacitance & Floating Capacitance

[viks_iisc]

Hi Guys,

I am looking for some numbers so as to get an idea of magnitude of top plate and bottom plate parasitic capacitance in MIMCAPs (data for other kind of capacitance implementation is also welcome ;-) ). Can this information be found in PDKs ?? Any paper on it is really welcome.

Second doubt i have got is suppose if i am having a floating capacitance in my circuit. How does it affect my circuit. Does it really affect. My thinking is that a floating capacitance is not really floating due to presence of the parasitic capacitances. Please comment on it.

 

[keith1200rs]

You should be able to find the capacitance of the lower metal layer in the process documentation. It *should* be included in the model. It can have a significant effect and can be quite a high proportion of the plate capacitance - up to 50%! So, you need to take it into account if the model in the PDK doesn't.

Keith.