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instrumentation amplifier and anti-aliasing

P

Ponkan

Jan 1, 1970
0
Hi,

I was wondering if I could "integrate" easily a low-pass filter (for
ADC anti-aliasing purpose) in an instrumentation amplifier.
I would not want to include an active filter between the
instrumentation amplifier (the ADC buffer) and the ADC itself. Just
wanted to use to the instrumentation amplifier to do the job. Any
idea? For the instrumentation amplifier I was thinking of the
Burr-Brown INA128 and for the ADC the Burr-Brown ADS7813. The ADC can
work at up to 40kHz and I would like to limit the input bandwidth to
10kHz. Maybe a simple RC between them is enough... I would like to see
your points of view.
 
R

Robert Baer

Jan 1, 1970
0
Ponkan said:
Hi,

I was wondering if I could "integrate" easily a low-pass filter (for
ADC anti-aliasing purpose) in an instrumentation amplifier.
I would not want to include an active filter between the
instrumentation amplifier (the ADC buffer) and the ADC itself. Just
wanted to use to the instrumentation amplifier to do the job. Any
idea? For the instrumentation amplifier I was thinking of the
Burr-Brown INA128 and for the ADC the Burr-Brown ADS7813. The ADC can
work at up to 40kHz and I would like to limit the input bandwidth to
10kHz. Maybe a simple RC between them is enough... I would like to see
your points of view.

I would think that a simple RC filter from opamp to ADC would be
adequate, provided you do not mind the rolloff in the desired signal as
well as the phase delays.
Setting the 3dB point at or below the sampling rate will erasonably
reduce the sampled signal level above the sampling rate; combined with
the reduced sampling sensitivity, the attenuation may be more than
adequate if you are not fussy.
 
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