ADG2128, analog signal range


Please let me ask you about Analog Signal Range of ADG2128 which is defined as VDD-2V(V max) in its's datasheet.

Q1) We did test on the EVB which is equipped ADG2128 "Y" grade part, and observed it is actually restricted/clipped at VDD-1V(approx.) more than specified(VDD-2V) as shown in attached doc.

Since it is still in the scope of Absolute Maximum Ratings, and there is no description of input range on negative side,

do you think we can actually input analog signal until VDD-1V and just above VSS on negative side, without any problem ?

or we should follow and keep the analog input range which is described as VDD-2V ?  

Q2) Deducing from the testing result, we are considering to choose AVDD=+7V, and AVSS=-6V.

Could you please make sure whether it is available or not, to be different amplitude between positive and negative supply on dual-supply application ?

Best Regards,