Quote Originally Posted by arr_baobao View Post
If the cap act as a decoupling role, mean that it always connected shunt?
Many cases, yes.

Quote Originally Posted by arr_baobao View Post
any decoupling cap that connected in series?
Small series capacitor is sometimes used as "weak coupling capacitor".
So it could work as "decoupling".

https://en.wikipedia.org/wiki/Decoupling_capacitor