JEE MainPhysicsSemiconductors
The digital input signals A and B , and the output signal Y of a logic circuit are observed over a time period from t=0 to t=4 seconds. The logic states (HIGH as 1, LOW as 0) change every second as follows: From t=0 to 1 s: A = 0, B = 0 From t=1 to 2 s: A = 0, B = 1 From t=2 to 3 s: A = 1, B = 0 From t=3 to 4 s: A = 1, B = 1 The output Y is observed to be HIGH only during the interval from t=3 to 4 s, and LOW otherwi
Options
- AA single NOR gate with inputs A and B .
- BA NOR gate with inputs A and B , whose output is connected to both inputs of a second NOR gate.
- CInput A is connected to both inputs of a first NOR gate, input B is connected to both inputs of a second NOR g
- DInput A is connected to both inputs of a first NOR gate, and its output is connected along with input B to the
Correct answer
C. Input A is connected to both inputs of a first NOR gate, input B is connected to both inputs of a second NOR g
Step-by-step solution
From the given time intervals, we can construct the truth table for the circuit: When A=0, B=0 Y=0 When A=0, B=1 Y=0 When A=1, B=0 Y=0 When A=1, B=1 Y=1 This truth table corresponds to an AND gate ( Y = A B ). Now, let us evaluate the given circuits constructed using NOR gates: Option 1: A single NOR gate gives Y = A+B . Option 2: The first NOR gate gives A+B . The second NOR gate acts as a NOT gate, giving Y = A+B + A+B = A+B (OR gate). Option 3: The first two NOR gates act as NOT gates, producing A and B . The th