Transistor Circuits - Current Source, Current Mirror, Voltage/Bandgap Reference

[@ife.tugraz]

This video is part of the first course of our *ElectrONiX* massive open online course (MOOC) series. You can sign up for the course *ElectrONiX - Amplifiers* for free on the following links: English: imoox.at/mooc/local/landingpage/course.php?shortname=amps&lang=en German: imoox.at/course/amps Bosnian: imoox.at/mooc/local/landingpage/course.php?shortname=amps&lang=bs

[@kabandajamir9844]

The world's best teacher thanks

[@ife.tugraz]

Thank you, we will pass your feedback on to Patrick.

[@jeffberhow]

Excellent video with great pacing

[@ife.tugraz]

Thanks for your nice comment.

[@Cesar_III]

Nice intro to the band gap reference.

[@ife.tugraz]

Thank you!

[@Klythia]

ΕΥΓΕ ΠΑΤΡΙΚΙΕ.... EXCELLENT ♥️♥️♥️🇬🇷

[@toucansam7032]

This is a great video! I have one question though: if you just need transistors with the same base-emitter voltage to make a current mirror, why does the base need to be connected to the collector of one of the transistors? Why can't the base be connected to some other voltage source?

[@joet4348]

I’m still learning the details of this too, but here is my response: You could have an independent voltage source connected to both bases, but then it wouldn’t really be a mirror (the transistor current on the right would not be copying the transistor current on the left). You would effectively end up with 2 individual, parallel current sources like the one at 1:07 and they’d be set to the same output current. Then I suppose you would be using the independent voltage source to set both output currents, rather than using the current in the left transistor to set the current in the right transistor. If you just wanted a constant current source using the current mirror, I guess you’d be adding extra complexity because you’d need to have another voltage source to set the current. In the current mirror, the base-emitter junction is fairly constant so it provides that voltage source for you if you just connect the base to the collector and you don’t need an extra voltage source.

[@toucansam7032]

@@joet4348 I see: so if the bases were connected to the same independent source, they would have the same current, but that's not the function of a current mirror. That makes sense. Thank you for the explanation!

[@mazen723]

It all starts here, if you're in for more of what is hidden in Transistor design. kzbin.info/www/bejne/o2qpf5d4ic1gr80

[@mazen723]

​@@joet4348 Hi ,there is more on this in my series of lectures, on Transistor design and Applications. Enjoy kzbin.info/www/bejne/o2qpf5d4ic1gr80