current controlled source

[pandit_vlsi]

hi all.
in current controlled voltage source for ex:a bipolar transistor,if current controlles o/p voltage ,from where this input current comes. it should have voltage no...then how this become current controlled..
pandit

 

[tamerakshar]

hi,
why do you say it need no voltage?
don't you understand transistor biasing.
this current comes from biasing voltages of the transistor,(Vbc).
transistorsmust have input voltage to operate.
Take a look to this Emitter follower.

 

[Hughes]

Although the output voltage will relate to the input voltage since the input voltage is usually depended on the input voltage, however, it is not voltage but current which directly determines the output voltage/current. The input current not always fully determined by the input voltage. When a bipolar transistor is exposed to light, there will be light-excited current. This light-excited current will also cause the output current to change. So it is current-controlled.