TS3A227E: TS3A227 design issues

Allan,

Some questions about TS3A227E need help
1. Is GND_SENSE directly connected to the GND of the TS3A227E? (TI E2E seems to say so)

Yes, GND_SENSE is directly connected to GND based on the internal switch matrix.

2. Can the TS3A227E and MIC Amplifier be common ground?

This will depend on your circruit and desired function.  The TS3A227E typically is used to select between the mic and ground path based on the type of headphone is inserted into the audio jack.  Do you have a diagram of what you are wanting to achieve that might make it more clear?

3. Are there any relevant known noise measures?

Below is the THD spec in the datasheet

Thank you,

Adam