Log In
2 votes

The gates G1 & G2 in the figure have propagation delays of 10ns and 20ns respectively. If the input Vi makes an abrupt change from logic 0 to 1 at time t=t0 , then what's the output waveform V0 is ? 

Also please explain how to handle such kinds of questions of waveform? 


in Digital Logic 1.5k views

@Gitika Babbar

Is the answer (c) ?


@ankitgupta.1729 no the answer is option B.. 

and I don't know how to solve such questions

2 Answers

6 votes



Note: The 20 ns delay due to EX NOR is actually EX OR. Apologies for the same.

How to solve such questions??

    The best way to solve such kind of problems is through timing diagrams. The delay in the circuit can be caused due to the gates or due to non inverter buffers.

    You should take it step by step. Based on the given input, deduce the output without considering the time delays(Look for G1 and G2 in the above diagram). Then, you need to just shift the diagram based on the delay(Look for V1 bar and V0 in the above diagram).

    The output of G1 depends on on V1 as the input is same.

    The output of G2 depends on both V1 bar and V1.

Thus, answer to the above question is option (B).

please provide some resources/ reference for such problems.

Take a look at this question and go through the discussion given, you will get an idea.

0 votes

Check out this video to get detailed explanation on this question.

reshown by

Related questions

3 votes
2 answers
5 votes
1 answer
Let X be the number of AND gates required and Y be the number of OR gates required in 4-bit Carry lookahead adder . Then what is value of 2X+2Y? My doubt here is they are just talking about AND and OR gate but usually we use AND,OR as well as XOR gate in CLA adder, Do we need to expand XOR gate and consider the AND and OR gate? Please Explain ?
asked Nov 14, 2016 in Digital Logic Prajwal Bhat 339 views