Question 94: Semiconductors and Logic Gates

Question

If VA and VB are the input voltages (either 5V or 0V) and V0 is the output voltage then the two gates represented in the following circuit (A) and (B) are :-

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

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 VA and VB are the input voltages (either 5V or 0V) and V0 is the output voltage then the two gates represented in the following circuit (A) and (B) are :-

Choose the correct answer: