using a femtofarad capacitor in RF design

[s_ss]

Hello all,

I am designing an RF amplifier and in my design if I use a capacitor of 55fF between two stages, my S21 becomes smooth and wide as I need. The question is...is it ok to use such a small capacitor in RF design because it will be having a very high impedance and may be an open circuit or we shall consider that some small signal will be going?

An early response will be highly appreciated.

Regards

 

[erikl]

Of course this is ok. For the layout you have to consider the parasitics, and probably you'll have to change its value.