Question 100: Semiconductors and Logic Gates

Question

If V
A
and V
B
are the input voltages (either 5V or 0V) and V
0
is the output voltage then the two gates represented in the following circuit (A) and (B) are :-
![](https://imagex.cdn.examgoal.net/1kujww9ff/056222c0-7f79-4eea-9d78-31f8a98aaaeb/db54f8b0-290f-11ec-b648-5143843e279d/file-1kujww9fg.jpg)

Accepted Answer

V
A
= 5V $\Rightarrow$ A = 1
V
A
= 0V $\Rightarrow$ A = 0
V
B
= 5V $\Rightarrow$ B = 1
V
B
= 0V $\Rightarrow$ B = 0
If A = B = 0, there is no potential anywhere here V
0
= 0
If A = 1, B = 0, Diode D
1
is forward biased, here V
0
= 5V
If A = 0, B = 1, Diode D
2
is forward biased hence V
0
= 5V
If A = 1, B = 1, Both diodes are forward biased hence V
0
= 5V
Truth table for I
st
$	herefore$ Given circuit is OR gate
For II
nd
circuit
V
B
= 5V, A = 1
V
B
= 0V, A = 0
When A = 0, E - B junction is unbiased there is no current through it
$	herefore$ V
0
= 1
When A = 1, E-B junction is forward biased
V
0
= 0
$	herefore$ Hence this circuit is NOT gate
![](https://imagex.cdn.examgoal.net/1kujx16fg/2d2822ad-9632-49bd-b14c-0d778db964e0/640f69b0-2910-11ec-8ce1-838231141173/file-1kujx16fh.png)

Answer

AND and OR Gate

Answer

OR and NOT Gate

Answer

NAND and NOR Gate

Answer

AND and NOT Gate

Semiconductors and Logic Gates

If V A and V B are the input voltages (either 5V or 0V) and V 0 is the output voltage then the two gates represented in the following circuit (A) and (B) are :-

Choose the correct answer: