I want to use the ADS1298 for EMG recording. To obtain an understanding of this device, I've got the Analog Evaluation Model ADS1298ECG-FE.
For reducing noise from the cables, caused by movements and capacitive coupling, it's necessary to use active shielding. Therefor I want to use the Right Leg Drive Signal by inserting the TLV2221 as shield driver. Unfortunately I don't understand the calculation of RLDOUT and RLDINV respectively (Figure 47, ADS1298 datasheet).
What happens after the PGAs and which influence have common-mode signals and difference signals? I can't find a logical relationship between INxP, INxN, RLDOUT and RLDINV.
Is the only task of the external elements (R=390k; C=10nF) to provide a low pass filter with RLD_AMP? And if so, I miss an additional resistor at the 'inverting input' of RLD_AMP to calculate the properties of the filter (similar to an active low pass filter, realised by an operation amplifier).
Thank you for your help!