Why does the output voltage of the transistor voltage regulator circuit equal the base voltage minus VBE?

小太阳yy

Why does the output voltage of the transistor voltage regulator circuit equal the base voltage minus VBE? [Copy link]

 

Why does the output voltage of the transistor voltage regulator circuit equal the base voltage minus VBE?

Why is the output voltage not equal to the input voltage minus the VCE voltage? Aren't these two contradictory?

maychang

"Why is the output voltage not equal to the input voltage minus the VCE voltage? Aren't these two contradictory?"

"The output voltage is equal to the base voltage minus V BE " and "The output voltage is equal to the input voltage minus V CE " are the same thing.

The transistor works in a linear amplification state, and the transistor will automatically change V CE to make the output voltage equal to the base voltage minus V BE . Only when the output voltage is equal to the base voltage minus V BE , the circuit can be in a balanced state.

maychang

It seems that you haven't figured out the reference points for V CE , V BE , and the "base voltage".

The V CE reference point is the transistor emitter, the V BE reference point is the transistor emitter, but the "base voltage" reference point is the ground, that is, the negative input pole, and of course it is also the negative output pole.

明月半倚深秋i

Vbe is fixed, Ve should be determined by Vb, and Vce is adjusted according to the circuit conditions.

chunyang

I suggest you re-learn the relevant chapters on the basic circuits of transistors in the basic analog part of electronic technology.