#### Jo999

##### Newbie level 3

I have to design an anti-aliasing filter. The parameters I have are:

Sampling frequency: 50kHz

Voltage range: +-2v, so 4 volt range

Bits: 14

Passband: 2kHz

Noise: 5E-4v (minimum detectable signal)

Looking around, it seems that the noise of my system will determine what attenuation I should have at half the sampling frequency. I asked the demonstrator for my class how to determine the minimum attenuation required for the system and he said that the signal at half the sampling frequency should be less than the SNR of the system so that when the frequency components above half the sampling frequency 'fold back', it will be less than the overall noise.

Only thing is, I can't figure out how to compute what the attenuation should be at half the sampling frequency given these values. It seems logical to me that before you calculated that, you would have to know what the strength of your signal was above these frequency components. If you don't have high frequency signals, no point attenuating what isn't there...

If you could shed some light, I would be grateful, especially if it has maths to back it up.

Regards,

Jo