Digital Circuits

To determine the truth table for the given circuit, we need to analyze the logic gates step-by-step. The circuit consists of two XOR gates whose outputs are fed into an OR gate.

Let’s break down the circuit:

1. The first XOR gate takes inputs A and B. The XOR gate produces an output according to the rule: .
2. The second XOR gate also takes inputs A and B and similarly produces: .
3. The outputs from the two XOR gates are then fed into an OR gate. The OR gate performs: .
4. However, since the outputs are identical, this is essentially .

Since both XOR gates have the same functionality and inputs, the output of the OR gate is determined by the XOR condition itself. Let's construct the truth table:

Thus, the truth table for the circuit is:

The correct answer is Option 2, which matches the truth table derived above.

1. Boolean expression:

2. Gate configurations:
- A. One 3-input AND gate, 3 NOT gates and one 2-input OR gate, One 2-input AND gate
- B. One 3-input AND gate, 1 NOT gate, One 2-input NOR gate and one 2-input OR gate
Therefore, the correct answer is (2) A,B Only.

We are given a digital logic circuit where both inputs are logic 1 (HIGH). We need to determine the outputs and .

Concept Used:

Each logic gate performs a standard Boolean operation:

• AND gate: Output = 1 only if all inputs are 1.
• NAND gate: Output = NOT(AND) = 0 only if all inputs are 1.
• OR gate: Output = 1 if at least one input is 1.
• NOT gate (inverter): Output = complement of the input.
• NOR gate: Output = NOT(OR).

Step-by-Step Analysis:

Step 1: Identify inputs.

Both upper and lower inputs are given as logic 1 (HIGH).

Step 2: Top-left gate:

It is a NAND gate (AND gate with a bubble at output). Inputs = 1 and 1 → AND output = 1 → NAND output = NOT(1) = 0.

Step 3: The output of this NAND gate (0) goes to two places:

- One input of the lower-left OR gate. - One input of the rightmost AND gate (for P).

Step 4: Bottom-left part:

The OR gate receives two inputs: - One is directly 1 (the lower input line). - The other is 0 (from the NAND gate). So OR output = 1.

Step 5: The OR gate output passes through a NOT gate:

NOT(1) = 0.

Step 6: This 0 goes into the NOR gate (the second circle with OR shape + bubble at output) along with the direct upper input (1).

NOR gate inputs: 1 and 0 → OR = 1 → NOR output = NOT(1) = 0.

Step 7: Now find P:

The rightmost top AND gate receives: - One input = output of the first NAND = 0. - Another input = top input = 1. AND(1, 0) = 0.

Final Computation & Result

Correct Option: (2)

Since the potential at and is the same, no current flows through the middle resistor (30 ).
The two parallel branches consist of: The equivalent resistance: The total current using Ohm’s law: