GATE CSE
First time here? Checkout the FAQ!
x
0 votes
96 views
For the circuit shown in figure, the delays of NOR gates, multiplexer and inverters are 2ns, 1.5ns
and 1ns, respectively. If all the inputs P,Q,R,S and T are applied at the same time instant, the
maximum propagation delay (in ns) of the circuit is _______


 

asked in Digital Logic by Boss (7.9k points) 6 41 119 | 96 views

1 Answer

+1 vote
In mux output will depend upon select line, when S = 0, input line 0 will be selected, when select line, S =1, input line 1 will be selected.

Considering S0 = select line of first mux, S1 = select line of second mux.

Case 1 : when T = 0, S0=0 and S1 = 1
Propagation delay= Delay due to input 0 (Nor gate, Since S0=0) + Delay due to MUX1 + Delay due to input 1(Since S1 =1) + Delay due to MUX2
So propagation delay = 2ns + 1.5ns + 0ns+ 1.5ns = 5ns

Case 2 : when T =1, S0 =1 and S1 = 0
Propagation delay = Delay due to input 1 (Not gate, Since S0=1) + Delay due to MUX1 + Delay due to input 0(Nor gate,Since S1 =0) + Delay due to MUX2
So propagation delay = 1ns + 1.5ns + 2ns+ 1.5ns = 6ns

Maximum propagation delay = max(case 1, case 2) = max ( 5ns, 6ns) = 6ns.
answered by Boss (6.4k points) 3 11 32
edited by


Quick search syntax
tags tag:apple
author user:martin
title title:apple
content content:apple
exclude -tag:apple
force match +apple
views views:100
score score:10
answers answers:2
is accepted isaccepted:true
is closed isclosed:true
Top Users Oct 2017
  1. Arjun

    23324 Points

  2. Bikram

    17048 Points

  3. Habibkhan

    7808 Points

  4. srestha

    6222 Points

  5. Debashish Deka

    5430 Points

  6. jothee

    4958 Points

  7. Sachin Mittal 1

    4772 Points

  8. joshi_nitish

    4286 Points

  9. sushmita

    3964 Points

  10. Rishi yadav

    3794 Points


Recent Badges

Nice Comment junaid ahmad
Popular Question iarnav
Notable Question makhdoom ghaya
Popular Question LavTheRawkstar
Avid Voter atul_21
Popular Question hem chandra joshi
100 Club nikhil_cs
Notable Question Sukannya
Notable Question Sourabh Kumar
Notable Question shikharV
27,287 questions
35,135 answers
83,911 comments
33,223 users