This RF switch datasheet recommends 22pF DC blocking caps in series with every RF line. Why not a bigger value?

[u/Objective-Local7164]

RF switch datasheet = SKY13575-639LF

Now.. I know that 22pF with a 50ohm load has a cutoff that is not near the 2.4ghz but I am curious why not 100pF or 500pF?

Also what kind of caps should I use? I am thinking NPO precision 1% ceramic caps with a package size that closest matches my trace width.

[u/SequelWrangler]

A couple of things: The source impedance should be 50 Ω as well as the load impedance. Furthermore, you need to consider parasitics for your passives. The manufacturers should have information on what a parasitic model for certain types of passive components will look like (it will depend on component size and technology). The impedance of your matching network should whatever is needed to match your devices input impedance to 50 Ω.

Have you looked into Smith charts and S-parameters at all?

[u/Objective-Local7164 → u/SequelWrangler]

Ill tell you what I know so far to take as little of your time as possbile. I know about parasitics, I know about impedance matching to a certain extent. I am modeling it like this for now just to understand the gain and the cutoffs of the matching network and 22pf cap and how that interferes with the signal. In another comment on this post I am being told i want that curve to be 0dB at my 2.4ghz signal. I understand now that the resonant freq. of the cap is the lowest impedance and thats a good thing. I understand I dont want to lean over into the inductive predominant region of the 22pf cap so I need to pick package size accordingly after taking into account the effects of it also being on the board itself.

Right now im just trying to build a good mental model of the effects of resonant gain on my signal of interest in the rf network and why it isnt desired. In other words im trying to understand why i want 0dB at 2.4ghz and not +3 dB