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Test
Your EQ #144— Answer
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Answer
3
Let VIH denote logic high voltage and VIL denote logic
low voltage. If V1 > VIH, Q1 is saturated and Vo = VCE(sat).
Similarly, if V2 > VIH, Q2 is saturated and Vo = VCE(sat).
Furthermore, if Q1 and Q2 are both saturated, Vo = VCE(sat).
However, if both V1 and V2 are less than VIL, Q1 and Q2
are cut off and Vo = Vcc.
| V1 |
V2 |
Vo |
| 0
(< VIL) |
0
(< VIL) |
1
(VCC) |
| 0
(< VIL) |
0
(> VIH) |
0
(VCE(sat)) |
| 0
(> VIH) |
0
(< VIL) |
0
(VCE(sat)) |
| 0
(> VIH) |
0
(> VIH) |
0
(VCE(sat)) |
The
truth table is as shown below: Therefore, the circuit
functions as a NOR gate.
Contributor:
Naveen PN
Published: July-2002
