Use of LC filters below 1 MHz

[parra]

Years ago I learned that passive CL filters have less losses than passive RC filters, as, if they are in resonance, have almost no resistance. Also, to get a 2nd order filter, you need just two elements (1 x C, 1 x L) compared to four elements you'd need for a 2nd order RC filter (2 x R, 2 x C).

Though, if you look at real world circuits, RC filters seem to be prefered as long as your corner frequencies are not in some MHz. What's the reason why LC filters aren't used instead?

Of course low frequencies mean big L's, but even for some µH the ohmic part of a inductor usually doesn't get bigger then 1Ω, so the losses must still be well below an RC filter.

 

[Phytech]

At low frequency, inductance becomes very big and expensive, and low Q sometimes. But 1 MHz is still good for LC filter design, though it's much more expensive than RC filters.

 

[saruman1983]

LC filters are by nature narrowband and may be preferred in such (narrowband) applications. Additionally, the gain is not quite constant at the in-band frequencies comparing to RC or RL filters.So, I believe the kind of the application determines which kind of filter is better to be used.

 

[parra]

Thanks alot for your replies, I think I've got it now