Why is a BJT called as 'current controlled device'?

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Dineshkumar005

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1. Why is a BJT called as 'current controlled device'?
2. Why is a FET called as 'voltage controlled device'?
 

Re: BJT and FET - current and voltage controlled devices

A BJT needs at the most .8V of drive to its base but may require up to 100mA of current. A FET requires 5V of drive to its gate but at 0 current.
Frank
 

Re: BJT and FET - current and voltage controlled devices

That's the same:
ic = Iss eΛ(VBE/Vt) as you can see the collector current ic is controlled by vBE

iS = 1/2 k'n W/L (vGS - vT) here iS, source current, is controlled by vGS (for saturation operation)
 

Re: BJT and FET - current and voltage controlled devices

in BJTs, the collector current can be controlled by base current Ic = (beta) Ib
in FETs, the drain source can be controlled by the channel voltage
 
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