The following description is given for the NC pins on the ADL5566 differential amplifier :
"No Connect. Do not connect to this pin. Solder to ground."
Now if you look at the application information and also at the evaluation board, all the NC pins are indeed connected to ground
On the first version of our board the designer left all those pins unconnected probably because he taught they were real NC pins.
We are now experiencing and evaluating some channel crosstalk problems and we wonder if it would help to actually ground all of these pins since on the chip layout they look like they are seperating the channels, or if they really are internally NC pins.
The package is very small, therefore it is pretty hard for us to try to short all these pins to ground so this is why I am asking for an opinion on this.
If there really is an effect on the interchannel isolation of soldering these pins to ground, they should be defined as GND pins and not NC, IMO.