Hello Gary,
The temperature sensor for the 'QG8 consists of a single diode, presumably fed by a constant current source. The voltage drop across the diode is measured.
For the 'AC16 device, it would be reasonable to assume that the sensor now consists of two diodes connected in series, to effectively double the resolution of the temperature measurement.
The calibration processes described in AN3031 should still be applicable to the later device. Note that the variation of the readings for different Vdd voltages, as graphed in the application note, is primarily because of the similar variation of Vref for the ADC module (Vref = Vdd).
Regards,
Mac