Sample Paper for Digital Electronics
Digital Electronics
Sample Paper
Note: Attempt any five questions.
1. What are Registers?Why are they used in digital electronics?
Ans: Registers are data storage devices that can store a group of bits.They are the cascaded group of flip flops.
2. Derive the boolean expression for the following logic circuit:
Figure:1
Ans: C(A+B)DE
3. From the truth table below,determine the standard SOP boolean expression:
Figure:2
Ans: Abar Bbar C + Abar BC + ABCbar
4. Define the various logic gates used in digital electronics.
Ans: The various logic gates are:
i) AND GATE= a.b
ii) NOT GATE = a bar
iii) OR GATE = a+b
iv) EXOR GATE = a bar b + b bar a
v) NOR GATE = (a+b) bar
5. What is S-R flip flop.Define its implementation.
Ans: S-R flip flop is a circuit that has two stable states and can be used to store state information.
Figure:3
6. Determine the output frequency for a frequency division circuit that contains 12 flip flops with an input clock frequency of 20.48MHz.
Ans: 5 KHz
7. What is race around condition?
Ans: In J-K flip flop, when the value of J and K =1 and at the same time value of clock is 1,so according to the truth table of J=K=1, the output should be toggled so the value keeps on changing till the change in clock pulse,which is not acceptable.
8. What is an ADC?Explain with an example.
Ans: An analog to digital converter is a device that converts a continuous physical quantity to a digital number that represents the quantity’s amplitude.
Example: ADC0808
Figure:4
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