Q factor for Varactor?

i have came across the Q factor for Inductor.

1.)how about finding the Varactor Q and value? The varactor is either pn-diod or mos-cap.

2.)how the measure the s-parameters of the varactor?

Hi RC13

The Q of a varactor is mostly expressed via its series resistance Rs.
You can calculate Q = Lw/Rs then.

I have not yet done myself measured the S parameters of a varactor but I guess you can do with a network analyser and measuring the S11.
Of course you must be able to provide the necessary bias for the varactor via a DC bias network (depends on your reflection bridge).

rgds

There is a big variation between brands. There seems to be some other characteristic that makes for high or low phase noise and is not strictly related to the advertised Q. It may be leakage current or something. You should try several brands to get the ones that work best in your application.