Operating Region of BJT in Temperature to Voltage Converter

[prietess]

Hello!

I am attaching the question that I am talking about (added 2 pages).

Please look at the pictures attached.
Let's say the temperature range is 20 to 45deg.
May I ask, for a simple Temperature to Voltage Converter with BJT as shown in this picture, does the BJT has to work in active region (with current gain) for all the temperature range from 20 to 45?

Or actually the correct implementation is that the BJT works in saturation for 20, then works in active region for 45 such that we have some transition of operating region that will help us identify the temperature change as well, and hence the temperature sensor is actually working fine?

I am a little bit confused. Because logical thinking might suggest that BJT has to be in active (in amplifying stage) when it is operating for some function other than a switch, but all my calculations are showing me that my BJT is transitioning from saturation into active region as it goes from 20 to 45.

At the second page, the question asks me to verify if another transistor with a higher beta=100 is suitable to substitute for the one in the question (beta=50)
But when I used beta=100, I also get saturation region when temperature is 20deg.

If my calculation says it is working in saturation for some temperature range, the question is wrong?

I really appreciate anyone who would be able to help!
Hope someone can help me please.
Thank you very much!

[bson]

Why don't you just put it on a breadboard and find out?