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Topic: Does the ADC has a builtin antialiasing filter? (Read 936 times) previous topic - next topic

Jun 15, 2013, 05:42 pm Last Edit: Jun 15, 2013, 08:21 pm by pauloborges Reason: 1
Hi,

I've already looked in the SAM3X datasheet and arduino.cc documentation, but without success.

I want to sample a signal whose highest frequency is greater than 1MHz but I'm only interested in the frequency range the ADC can sample. According to Nyquist–Shannon sampling theorem we must sample the signal with a sampling rate >= 2 * signal highest frequency or we will get alias.

This can be fixed with a LPF with a cut frequency equal to ADC sampling rate / 2. But what I want to know is if the SAM3Xs ADC (and others ucontrollers ADCs) already has this LPF inside it.

pito

#1
Jun 18, 2013, 07:49 pm Last Edit: Jun 18, 2013, 07:54 pm by pito Reason: 1
Quote
But what I want to know is if the SAM3Xs ADC (and others ucontrollers ADCs) already has this LPF inside it.

No, most ucontrollers do not have LPF built in.
Long time back I used to use
http://www.maximintegrated.com/datasheet/index.mvp/id/1899
http://www.maximintegrated.com/datasheet/index.mvp/id/1880
There are 3V and 5V models available.
And a lot of others:
http://para.maximintegrated.com/results.mvp?fam=filt

#2
Jun 19, 2013, 01:44 pm Last Edit: Jun 19, 2013, 01:46 pm by dan@togglebit.net Reason: 1
Practically in industry you will find : 10x rather than 2x sample rate to reconstruct a signal and AAF cuttoffs set to 1/3 to 1/4 the sample rate. See the thread in this forum on data acquisition to empirically figure out max sample rate in a polling mode using the arduino libraries. I've been meaning to do a test and post results. http://forum.arduino.cc/index.php?topic=171993.0
Dan - www.togglebit.net - Arduino DUE proto shields - Arduino DUE CAN shields

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