Other Parts Discussed in Thread: ADS1299
I have two questions about the filter functions of ADS12898 and also ADS1299.
1) Mechanism of the common-mode rejection at 50Hz/60Hz (CMRR: -115dB).
Is the sinc filter used for50Hz/60Hz noise reduction ?
Is the DC offset between +input and -input cancelled ?
2) How to use sinc filter
Two cables at least must be used for EEG application.
The cables pick up 50Hz/60Hz noise. It is impossible to avoid the such circumstance.
When normalized frequency is set to 1, indeed 50Hz or 60Hz noise can be suppressed。
However the necessary signal is also suppressed due to sinc filter characteristics like Figure 52 in the data sheet.
Please tell me how to use sinc filter when we'd like to suppress 50Hz or 60Hz and don't like to suppress signal in band for example 40Hz.
Thanks,
M. Ogawa