# JEE Main & Advanced Physics Semiconducting Devices The 'NOT' Gate

The 'NOT' Gate

Category : JEE Main & Advanced

(1) It has only one input and only one output.

(2) Boolean expression is $Y=\bar{A}$ and is read as 'y equals not A'

(3) Realization of NOT gate : The transistor is so biased that the collector voltage ${{V}_{cc}}=V$ (Voltage corresponding to 1 state) The resistors R and ${{R}_{1}}$ are so chosen that if the input is low i.e. O, the transistor is in the cut off and hence the voltage appearing at the output will be the same as applied V. Hence Y = V (or state 1) If the input is high, the transistor current is in saturation and the net voltage at the output Y is 0 (in state 0)

(4) Truth table for NOT gate :

 A $Y=\bar{A}$ 0 1 1 0

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