Hi Antonello,
Please find the answers below highlighted in red.
1.Would it be possible to operate the CW and TGC paths on the same time?
[Fabio] No, the part is designed to work either TGC OR CW. See register setting in the uploaded file. Otherwise, there is a test mode to route Ch7 and Ch8 PGA outputs to the CW output pins, but I doubt that helps you. Please tell me more about your application, as we have some MRI specific parts including the ADS5263 ADC.
2. How much it would affect the noise on the two paths and what would be the effect on the total power dissipation?
[Fabio] As you cannot run both TGC and CW mode, total power dissipation and noise performances are as per datasheet. Please refer to it
Hope it helps.
Fabio