The following figure shows a logic gate circuit with two inputs A and B and the output Y. The voltage waveforms of A, B and Y are as given. [figure] The logic gate is
- NOR gate
- OR gate
- AND gate
- NAND gate
Answer
(4) NAND gate
Solution
Reading the waveforms interval by interval:
0 to t1: A = 1, B = 1 Y = 0
t1 to t2: A = 0, B = 0 Y = 1
t2 to t3: A = 0, B = 1 Y = 1
t3 to t4: A = 1, B = 0 Y = 1
t4 to t5: A = 1, B = 1 Y = 0
The output is 0 only when both inputs are 1, i.e. Y = A B, which is the truth table of a NAND gate.
Answer: (4)