What is an anti-aliasing filter and how is it used?

[meldave00]

Hi,

Can anyone tell me what an anti-aliasing filter is and how it is used?

regards,

meldave

 

[chroot]

Aliasing is an undesired effect in the use of analog-to-digital converters. Frequency components above the the Nyquist band (above half the sampling frequency) get "mirrored" into lower frequencies inside the Nyquist band. Once a high frequency has been aliased, there is no way to distinguish it from a real low-frequency signal.

An anti-aliasing filter is a low-pass filter, put before the ADC, that attenuates frequency components above the Nyquist band.

- Warren

 

[meldave00]

Thanks. I appreciate it.