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Preamp for ads1246

Farooq Shah
Prodigy 30 points
Other Parts Discussed in Thread: ADS1246, ADS1259

I have an application that will need gain of 500-2000. Can I use LT1677 (ultra low noise) opamp to give it the additional gain? What care should I take for interfacing LT1677 to ADS1246? Do I need an anti-aliasing RC filter between? I must use single ended single supply design.

fshah

  • 0
    TI__Guru** 113765 points

    Farooq,

    I can't really speak to the LT op amp, but to have that much gain your signal must be really small.  Can you tell me a little more about your sensor?  What level of signal resolution are you trying to achieve? 

    One thing to consider is gaining up noise, as noise will determine the level of resolution you will achieve.  The ADS1246 requires an external voltage reference.  This must be very low noise as well.  You should have an anti-aliasing filter, and the values will be related to the data rate you choose to operate as data rate will determine the modulator rate.

    You must also consider that the ADS1246 has a common mode restriction on the input, and that the input is measuring differentially.  Using a unipolar supply, you cannot set the input to ground. 

    Another device option that you may want to look at is the ADS1259.  This device has better noise specifications as compared to the ADS1246, and can measure a signal referenced to ground.

    Best regards,

    Bob B