Logic Gate: Output High When Inputs Same
The question asks to identify a 2-input digital logic gate. The key condition is that its output is HIGH only when both inputs are the same.
Analyzing Logic Gate Functions
We need to find the gate whose output is logic 1 when its inputs are identical (both 0 or both 1). Let's examine the options:
- EX OR Gate (XOR): Produces a HIGH output when inputs are *different*.
- EX NOR Gate (XNOR): Produces a HIGH output when inputs are the same. This matches the required condition.
- AND Gate: Produces a HIGH output only when *both* inputs are HIGH.
- NAND Gate: Produces a LOW output only when *both* inputs are HIGH (inverse of AND).
Based on the functionality, the EX NOR gate is the correct answer.
EXNOR Gate Characteristics
The EXNOR (Exclusive NOR) gate, also known as the XNOR gate, implements logical equality. Its output is HIGH if and only if the inputs are equal.
The Boolean expression is:
Output = $A \odot B$
Or
Output = $\overline{A \oplus B}$
Where $A$ and $B$ represent the two inputs.
EXNOR Gate Truth Table
| Input A | Input B | Output |
|---|---|---|
| 0 | 0 | 1 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
The truth table confirms that the output is HIGH (1) exclusively when both inputs, A and B, are identical.
Important Questions from Logic Gates
A two-input logic gate is giving high output only when both the inputs are high. For all other input conditions, the output is low. Select the correct logic gate.
The output is high only if one of the input is high. The above statement represents _____
The number of gate inputs, required to realize expression ABC + AB̅CD + EF̅ + AD is
Which of the following is logically equivalent?
A. ¬p → (q → r) and q → (p ∨ r)
B. (p → q) → r and p → (q → r)
C. (p → q) → (r → s) and (p → r) → (q → s)
Choose the correct answer from the options given below :
Consider the expression Y = P ⨁ Q ⨁ R where P, Q, R are the input variables and Y is the output variable. Y will be logic 0 if
(A) an odd number of input variables are 1
(B) an even number of input variables are 1
(C) an odd number of inputs variables are 0
(D) an even number of input variable are 0
(E) an odd number of input variable between 0 and 1
Choose the correct answer from the options given below:
