Coil BW

Hello,

I need a coil (1uH) with a very large bandwidth, let's say 500 MHz bandwidth (DC to 500MHz).

I had a look on manufacturers websites but it seems I m dreaming.

Do you know such coils?

I assume you are looking for a choke.

A good choke shall have a reactance 10x greater than the operating impedance.
So for 50 ohms impedance the choke XL > 500 ohms.

1uH has XL=500 ohms at 80MHz, which means you can use it as a choke for frequencies greater than 80MHz.

I don't use it as a choke, I need a coil with a stable 1 uH inductance along a wide bandwidth.

But thank you for your comment, this explanation is really helpfull

An 1uH resonates at 500 MHz with about 0.1 pF parallel capacitance. To be "a stable inductance" at this frequency, the parallel capacitance must be considerably smaller than 0,1 pF. Sounds illusional indeed.

Just for yucks, I checked coilcraft. Much to my suprise, if you use two 491 nH coils in series, you can just squeek by.

I would orient the two coils at 90 degrees to one another. Depending on your application, you might want to place a resistor in parallel with each coil to de-Q any resonances.

http://www.coilcraft.com/maxi.cfm

Rich