I was looking through the design of this board, which uses ADS1299 for measuring EEG signals.
EEG signals have a freq band of usually about 5-100Hz and they are low in their SNR as well.
Before the signals from the electrodes (EEG) are received at the pins of the ADS1299, they first have TVS diodes connected to ground from them, and they go though this RC low pass filter (R = 2.2K, C = 1nF). So this would make a cutoff frequency of 72 KHz.
I have 2 questions about this design:
Am I correct in assuming that the TVS diode is there to clamp any voltage spikes (e.g. for static charges being discharged)?
What is the main purpose of the RC filter?