Yes it can be done, quite easily. I use a transformer and put the cap on the secondary side. A transformer consist of a voltage controlled voltage source and a current controlled current source.
This would be static in the sense that you set the control parameter before SPICE runs. Now if you want a dynamic controlled transformer, then you use B-elements, same thing thug a voltage to voltage B- element and a current to current B-element.
Why does this work, a transformer is an impedance reflection device for one aspect in the sense what ever is on the secondary is reflected to the primary by this simple equation:
Z_primary = Z_secondary x N(primary squared)/N)secondary squared)
Example let us say you have a transformer that has a primary to secondary ration of 1:10, one primary turn & 10 secondary turns. Now let say you have a 10-Ohm resistor on the secondary, what is reflected on the primary?
Ok that is 10-Ohms x (1/10) x (squared) = 10/100 = 0.10 Ohms
So that means if the primary voltage is say 10V, the the current is 10/0.01 = 100A.
Now what about a capacitor, the formula is still the same, where Z is simply the capacitor reactance.
I don't know what type of SPICE you are using and even if your SPICE supports B-elements, If it is fully compliant with the latest Berekely (3f4) version it will have B-elements. Although B-elements in SPICE is years old. And since I don't know I can't send you the syntax for the file. Below is a PDF of what I am talking about. Also you can simply Google to Yahoo, < transformer SPICE > to see what I am talking about in terms of representing a transformer in spice. Mind you this is not a complete transformer model that you would normally use (not explain that aspect) but what it does is reflect a secondary current over onto the primary voltage which is what is needed.
http://search.yahoo.com/r/_ylt=A0oGdVHHnnVQxT...0FDQlkwNF8xMDA-/SIG=129kreiam/EXP=1349914439/**http://www.edacafe.com/books/PSpice/san63267_ch01.pdf
I can send you something from what I use and you will have to figure out the rest or someone else can contribute. I'll mark up a diagram, with the spice list (syntax) and send that later after I scan it.
I use this quite often in filter design if I have say 20 complex ceramic caps in the circuit all the same and I want to see the effect of changing some of the cap variables on the filter response. I just change one control voltage and one parameter of my primary cap, and all 20 caps on the secondary are instantly changed.
