
3.6 | Chapter 3
Bipolar Junction Transistor Circuit for NOT
gate: Circuit is given in Figure 3.11.
• When input A is at 0 V (i.e. A = 0). Bipolar
junction transistor (BJT) remains OFF be-
cause transistor is not biased. No current
will ow through R. So there will be no
voltage drop across R. Hence output X is
at +5 V (approx.) (i.e. X = 1)
• When A is at 5 V (i.e. A = 1). Bipolar
junction transistor (BJT) is ON because
transistor is biased. Current will ow
through R. So there will be voltage drop
across R. Hence output X is at +0 V
(approx.) (i.e. X = 0)
NMOSFET Circuit for NOT gate: Circuit is
given in Figure 3.12, in which n-type ...