0
\$\begingroup\$

I want to buy inductor and capacitor for matching circuit of antenna in about 1.6GHZ. I searched the net for some inductor for example 3.7nH and i collided with lots of parameter!! I know concept of parameters like SRF & Q .But for example it told something like 25 @ 200MHZ, and witch SRF is better for me and why? I think about 2GHz is ok, isn't that? And i found no Q in 1.6GHZ.How can i chose these and other parameter? Please explain them.

\$\endgroup\$
1
\$\begingroup\$

witch SRF is better for me and why?

You need the SRF to be higher than your operating frequency, if you want your inductor to behave like an inductor and not a capacitor.

But for example it told something like 25 @ 200MHZ

Many rf parts will have available SPICE models or s-parameter measured characteristics. If you use a simulator that emphasizes rf design (like ADS), you can plug the s-parameter measurement file into a simulation block, and simulate the behavior.

And i found no Q in 1.6GHZ.How can i chose these and other parameter?

The Q factor lets you estimate the resistive loss in an inductor. If you also have a DCR value, it's mostly redundant information (although there could be skin effect increasing the loss at high frequencies). Again if you want to be sure, use the rough parameters (DCR, SRF, Q) to do an initial part selection, but then simulate your design using the more detailed models or typical measurements.

\$\endgroup\$
0
\$\begingroup\$

Do you understand what SRF is? If you understand that, then you can calculate the parasitic capacitance of the inductor. Before you jump into selecting inductors, make sure you know what that is.

As far as Q, you should select fairly (25 to 30 minimim) high Q inductors, measures at a high frequency.

I've had good luck with Coilcraft HQ inductors in high frequency applications, but they have terminations on the bottom of the part, so you really need a hot air soldering iron to swap them out, which you'll be doing if you're trying to do an impedance match. It's been a while since I comparison shopped inductors, so YMMV

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.