• State
  • Locked Locked
  • Replies 0 replies
  • Subscribers 45 subscribers
  • Views 312 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

InAmp needed for ADS1299 for EEG with passive electrodes?

Hang Zhang2
Prodigy 15 points
Other Parts Discussed in Thread: ADS1299

Hello,

I am trying to use ADS1299 for surface EEG signal acquisition with passive electrodes. Do I need to add pre-amp stage when I use ADS1299? The internal reference voltage of ADS1299 is 4.5v, and the resolution of the 24-bit ADC in ADS1299 would be 4.5/(2^24), about 0.27uV. Assuming an EEG amplitude of about 10uV and a PGA gain of 24, this gives me log2(10*24/0.27)=9.8bits. The datasheet shows that the noise with max oversampling and PGA gain 24 is about 5 bits. This would leave us with about 5 effective bits, which might be too small for my application (we still have to find out).

Do I need to add pre-amp stage to amplify the EEG signal before feeding it to ADS1299 to better utilize the resolution? Or can I just lower the ADC reference voltage (e.g. to 1V) effectively improving the ADC resolution for the voltage range of interest? In other words, how will the overall input referred noise change with a lower reference voltage?

Thanks in advance for your help!