Once again, thank you so much.
I'm sorry, but I still don't understand what you said.
You were talking about the additional capacitance. Is it different from the capacitance of coupling capacitors(C1,C2)?
If I can't neglect the coupling capacitors (270pF), I think their capacitances are quite higher than 4.7pF(C3)
And may I ask you one more question?
What topic/concept do I have to search/study in order to understand that two inductors are connected in face in series.
Sorry to keep bothering you.