ADC in Digital Temperature Sensor DS18B20
All you really need to know is contained here: -



Internally the device may have a sensor that produces 10uA per degree or 10mV per degree or it may be like a thermistor or RTD and vary its resistance to indictate temperature. This is Maxim IP and we are not allowed to know what method they use unless they tell us. If it's not in the data sheet then we cannot know - but you could assume it is one of the four methods I've mentioned and give details in your presentation of all ideas.

If you want to know the types of constant voltage or current sensors that could be used try looking up the AD590 (constant current at 10uA per degC) or the TMP36 (10mV per degC). I'm not aware of a particular name that describes the technology.