switched tuning

Normally, people use MIM or finger metal capacitor for high linearity. Anyone ever see paper use varactor or moscap as switched tuning capacitor array?

Pls suggest reference, thanks.

I have seen a varactor in parallel with selectable fixed capacitors. That way you get a bigger overall tuning range.

I suppose you could have the varactor in series with selectable fixed capacitors to do the same thing, but with better linearity.

I saw someone use switch inductor.

MiM is common method. because its Q is very high.

MOS is good also, but it parasitic is not precise.