Question

A pulse is applied to each input of a 2-input NAND gate. One pulse goes high at t=0 and goes back low at t=1ms. The other pulse goes high at t=0 and goes back low at t=3ms. The output pulse can be described as follows:

• A. It goes low at t=0 and back high at t=3ms.
• B. It goes low at t=0.8ms and back high at t=3ms.
• C. It goes low at t=0.8ms and back high at t=1ms.
• D. It goes low at t=0.8ms and back low at t=1ms.

Hint:

For NAND gates, the output is low only when both inputs are simultaneously high.

Answer 1

The Correct Option is B

For a 2-input NAND gate: 1. The output remains high unless both inputs are high. 2. At t = 0, both inputs are high, so the output goes low. 3. At t = 0.8 ms, one of the pulses changes state, causing the output to go high again. 4. The output remains high until t = 3 ms, when the second pulse goes low.