Input referred noise is kT/C thermal noise and thus will vary as the square
root of the temperature in degrees K. The input referred noise in the AD9649
datasheet is 0.98LSBrms. Over the temperature range -40 to 85°C this will vary
about +/- 10%. At 85°C it will be 0.98xsqrt(358/298) = 1.07LSBrms and at -40°C
it will be 0.87LSBrms.