I am new to circuit and has a very basic question about how to set biasing circuit of varactor. I need to use varactor to tune the resonance behavior of Split ring resonator (SRR) structure when illuminated by plane wave. (If you are not familiar with SRR, you can think that SRR illuminated by plane wave is just a RLC circuit driven by AC voltage), See Fig.1.
I tried to find some guidance online. Some said that I need to use RF choke (an inductor) to isolate DC voltage from AC circuit, see Ref.1. Somme said either inductor or resistor could be used, see Ref.2. Some uses both inductor and capacitor, see Ref.3. (Fig7, Page12). This make me confused, so, what should I do?
My own understanding is that, RF choke is to make the DC biasing circuit 'unseen' by AC signal, so, at working frequency of the AC circuit (f0), the impedance of inductor should be much larger than that of the varactor, so that the current flowing in the DC branch is negligible comparing to the AC branch,See Fig.2. Am I correct?
If there is anything wrong, please correct me. Besides, external resources could be helpful, too. I looked up several textbooks on circuit, but no detailed information about how to bias varactor was found.
Thank you very much for your kind help! (By Jingwei)