Re: temperature descranpancy between the junction and ambien
One cause of elevated junction temperature is self heating.
Any dissipation in the part results in some increase in junction temperature over ambient.
For small signal parts, there may be a high thermal impedance to the surroundings.
If this is true, tiny dissipations can make a measureable temperature rise.
You can choose from these approaches for simulation temperatures, or pick another:
1) Choose a standard temperature, such as 25 C.
2) Calculate dissipation, determine thermal impedance and then calculate temperature rise.
3) Measure a junction voltage on the divice in a real circuit and calculate the temperature from the diode equation.
4) Guess