filtering on noisy circuits?

[petervk]

Hi all,
OK I know (a bit) about shielding sensitive circits from other sources of noise in the system, but what should I do about the circuits that generate the noise?
Should I be putting such things as LC filters on the supply TO the circuit thats going to be making a racket (to stop supply noise feeding back into the sensitive bits), or is it better to keep a path of low impedance on both supply and ground for the noisy bits?

Cheers,
Pete

 

[IanP]

LC filters on supply lines stop noise and are more efficient than low-imedance option .. and on top of that obviously good shielding of sensitive circuits ..
Regards,
IanP

 

[sunking]

the differencial can help you inprove the peformance

 

[Kral]

Peterv,
Careful ground layout also helps. Arrange the ground returns for the senstive circuit such that no power supply current flows through the signal ground path to the circuit. This usually means using a separate ground plane for signals, or if you cna't use ground planes, use a "star" arrangement of grounds.
Regards,
Kral