Q7- We implement the 3-input NAND gate circuit as follow and we are given the gate delay of d ns and 3 inputs are shown as: And give us the output of the circuit and compare it with the ideal output. Ans: Firstly we NAND of A&B is calculated and then it is inverter to get […]

# Boolean Algebra

## Question 6: OUTPUT OF XOR CIRCUITS

Q6- What is the output of the circuits given below? Ans: Here we see that if we have X= 0 then outputs of both circuits is zero. But when we have X=1, then output of the circuit with even number of XOR gates is 1 And when we have X=1 and number of XOR gates […]

## Question 5: OUTPUT OF CIRCUIT

Q5- What is the output of the following circuit? Ans: This circuit may look simple to you as one has to just evaluate every NOR gate and get the final output but I say it is even simpler than this. Let’s analyze the truth table of NOR gate: And we see that even if only one […]

## Question 4: TIMING DIAGRAM

Q4- Draw the output waveform of the NAND gate when we have the two inputs as follow and delay of the gate is equal to 12.5 ns when output goes from LOW to HIGH and delay is 17.5 ns when output goes from HIGH to LOW. Ans: To get the exact output waveform we firstly draw […]

## Question 3: TIMING DIAGRAM (Diff Units)

Q3- Sometimes delay of gates and the waveforms are given in different units. So let’s take such example with same circuit and delay as above but waveforms as below: Ans: So we convert the delay into ps (Pico seconds) So delay for NOR= 3ns = 3000ps Delay for BUFFER =1ns=1000ps Delay for AND=4ns=4000ps So the waveforms […]

## Question 2: TIMING DIAGRAM

Q2- Draw the output of the circuit when waveforms of inputs X & Y are as given. Take initial output values as zero. We’ll first calculate output of NOR gate and delay the output by 3ns. Then we draw output of BUFFER with delay of 1ns and finally we take AND of 2 outputs and […]

## Question 1: TIMING DIAGRAM

Q-1 Show the level transitions in the input signal at the output line if Tp1 = 2ns, Tp2 = 2, Tp3=3ns, Tp4= 2 ns and assuming that all the transitions in input occur at t=0 Ans: At node A: We have transition after the delay of Tp1 = 2 ns and at t=2 a HIGH to […]

## Special Characteristics of an IC

A gate IC can be realized using different logic families (explained later) and hence every gate have the following characteristics which may vary with different logic family. The most important parameters are the following Fan-out: It specifies the maximum number of standard gates that output of a gate can rive without affecting its own working. This […]

## Division of the circuit in different levels

We have some eternal inputs which are used directly or indirectly by the elements of the circuit to obtain output. The elements or the gates which receive all their input from the external inputs directly constitute the logical level one of the circuit while the gates which receive at least one input from the output […]

## Question: Implement XNOR gate using NOR only

Q- Implement 2 variable XNOR gate using NOR only in minimum number of gates. F= x XNOR y = (x XOR y)’ F’= (x XOR y) = x’y+xy’ = x’y+xy’+xx’+yy’ = (x+y) (x’+y’) F’= x’(x+y) + y’(x+y) Take compliment F= (x’(x+y) + y’(x+y))’ = (x’(x+y) )’ . (y’(x+y))’ =(x+(x+y)’). (y + (x+y)’) Take compliment again […]