Filters

[Kevin Weddle]

What is the limitation of using filters that have better attenuation than capacitor and inductor filters?

 

[Hero999]

Filters are generally composed of capacitors, inductors and resistors so your qestion doesn't make any sense.

Do you mean active filters?

Yes, active filters do have the advantages of bbeing able to drive low impedance loads and have amplification whic passive filters do not.

 

[Kevin Weddle]

Hero99, there are a variety of filters available. Many designs use only LC filtering, but is it because other types of filters do not have the requirements to meet the design? Many filters have great response, but a narrow specification and might be intended for only a few applications.

 

[audioguru2]

While they were available, I used National Semiconductor LMF40 high performance 4th-order switched-capacitor Butterworth lowpass filter ICs for many applications.
The cutoff was sharp and could be tuned over a wide frequency range with the built-in clock oscillator or an external oscillator.
I even cascaded them in series for a very sharp cutoff.
The distortion was extremely low.

I used an LMF100 switched capacitor IC to make a tracking notch filter for my distortion analyser.

 

[Kevin Weddle]

I was refering more to passive component circuits involving crystals, ceramic filters, SAW filters and other technologies. And, aren't the passive components available today more capable of producing the desired filter response?

 

[indulis]

A "filter" with a crystal??

Care to provide an example?

 

[Hero999]

I'm sure it's possible but you'll need some damping otherwise the bandwith will be very tiny.