I am studying Transistors from the book: Arts of Electronics by Paul Horowitz and Winfield Hill (second edition). I have a few questions related to the working of a transistor, especially in the saturation region.
In the rule 1, as to the working a transistor, it has been mentioned: "The collector must be more positive than the emitter".
1. Why is that so?
2. And is it true only for that forward-active region or in all regions (i.e. saturation, cutoff, reverse-active)?
3. Also what would happen if the collector potential becomes less than that of the emitter potential?
Another query that I have is, 'does saturation imply a maximum value of current through the transistor? Or is the maximum value of current achieved before the device enters the saturation region (which I believe should be the case)?'
Edit: While reading a similar question on the website, I was directed to the link: Transistors in saturation region where a user (Studiot), explained the saturation from the perspective of an electronic engineer, he mentioned that the collector voltage can not be zero (or less than the emitter voltage, which is grounded in his circuit). Hence the saturation voltage can be around 0.2V - 0.4V.
Also I read that in the saturation region, it appears as if the emitter and collector are short-circuited, then why is there still a potential difference of 0.2V - 0.4V existing?