RF Chokes

[ronv]

I'm trying to build a power amp that runs at 66MHz. The circuit calls for an RF choke of 10 uh. When I look at data sheets for such inductors the self resonant frequency is either below or right around 66MHz. Do I need to worry about this? If so what is the solution? I've looked at ferrite beads but it looks like 2uh is about is big as I can find.

 

[Nigel Goodwin]

If it's an RF choke it's not going to matter, as it probably isn't a tuned component - just a decoupler.

 

[ronv]

Yes, it is just to decouple the RF from the supply.

Thanks!

 

[RadioRon]

Self Resonant Frequency of an inductor is that lowest frequency at which the inductor is a parallel resonant circuit, involving the device inductance and its parasitic capacitance. The point of a choke is to present a high impedance to RF and an inductor at self resonance is at its maximum impedance, so it would work fine. Above the SRF, there are other resonances that are less predictable unless measured, so its not a great idea to go very much above the SRF, as a rule of thumb.

 

[ronv]

Thanks for the input!