Subject: Re: Besides Q factor , how to classify RF inductor and choke ?

If you want a choke for isolation between RF and DC, you should consider:

(1) the value of inductance which determines the reactance that it
presents to the RF energy. Clearly, you want this reactance to be high
compared to the impedance in the RF circuit (normally 50 ohms, but may be
different depending on where you insert the choke).

(2) The DC resistance must be low enough that the voltage dropped across
the choke is negligible compared to the operating voltage of your power
amplifier's device.

(3) The current rating of the choke must be adequate to carry the
quiescent operating current of your circuit and then some.

(4) The self-resonant frequency of the choke must be higher than the
operating frequency of your circuit; otherwise you may have a capacitor
instead of an inductive choke in the extreme, or a complex reactance
function that may interact with your amplifier to produce spurious
modulation or even oscillation.

(5) The mechanical aspects of the choke, size, shape, shielding, mount,
and orientation will affect stray interaction in the circuit and must be
given some consideration.

(6) You must give consideration to thermal aspects of the design as well.
For example, if choke dissipation elevates its temperature and the choke
has a magnetic core, your circuit will experience poor isolation as the
core temperature approaches its Curie temperature.