EC1203 Digital Electronics B.E Question Bank : niceindia.com

Name of the College : Noorul Islam College of Engineering
University : Anna University
Degree : B.E
Department : Electronics and Communication Engineering
Subject Code/Name : EC 1203 – Digital Electronics
Year : II
Semester : III
Document Type : Question Bank
Website : niceindia.com

Download :https://www.pdfquestion.in/uploads/ni…lectronics.pdf

NICE Digital Electronics Question Paper

Unit – 1 :
Part – A :
1. Define binary logic? :
Binary logic consists of binary variables and logical operations. The variables are designated by the alphabets such as A, B, C, x, y, z, etc., with each variable having only two distinct values : 1 and 0. There are three basic logic operations: AND, OR, and NOT.

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2. What are the basic digital logic gates? :
The three basic logic gates are
**AND gate
**OR gate
**NOT gate

3. What is a Logic gate? :
Logic gates are the basic elements that make up a digital system. The electronic gate is a circuit that is able to operate on a number of binary inputs in order to perform a particular logical function.

4.Give the classification of logic families
**Bipolar Unipolar
**Saturated Non Saturated PMOS
**NMOS
**CMOS
**RTL Schottky TTL
**ECL DTL
**I I L
**TTL

5. Which gates are called as the universal gates? : What are its advantages?:
The NAND and NOR gates are called as the universal gates. These gates are used to perform any type of logic application.

6.Classify the logic family by operation? :
The Bipolar logic family is classified into

Saturated logic:
The RTL, DTL, TTL, I2L, HTL logic comes under the saturated logic family.

Unsaturated logic:
The Schottky TTL, and ECL logic comes under the unsaturated logic family.

7.State the classifications of FET devices.
FET is classified as
1. Junction Field Effect Transistor (JFET)
2. Metal oxide semiconductor family (MOS).

8.Mention the classification of saturated bipolar logic families.
The bipolar logic family is classified as follows :
**RTL- Resistor Transistor Logic
**DTL- Diode Transistor logic
**I2L- Integrated Injection Logic
**TTL- Transistor Transistor Logic
**ECL- Emitter Coupled Logic

9. Mention the important characteristics of digital IC’s? :
**Fan out
**Power dissipation
**Propagation Delay
**Noise Margin
**Fan In
**Operating temperature
**Power supply requirements

10. Define Fan-out? :
Fan out specifies the number of standard loads that the output of the gate can drive with out impairment of its normal operation.

11. Define power dissipation? :
Power dissipation is measure of power consumed by the gate when fully driven by all its inputs.

12. What is propagation delay? :
Propagation delay is the average transition delay time for the signal to propagate from input to output when the signals change in value. It is expressed in ns.

13. Define noise margin? :
It is the maximum noise voltage added to an input signal of a digital circuit that does not cause an undesirable change in the circuit output. It is expressed in volts.

14. Define fan in? :
Fan in is the number of inputs connected to the gate without any degradation in the voltage level.

15. What is Operating temperature? :
All the gates or semiconductor devices are temperature sensitive in nature. The temperature in which the performance of the IC is effective is called as operating temperature. Operating temperature of the IC vary from 00 C to 700 c.

16.What is High Threshold Logic? :
Some digital circuits operate in environments, which produce very high noise signals. For operation in such surroundings there is available a type of DTL gate which possesses a high threshold to noise immunity. This type of gate is called HTL logic or High Threshold Logic.

17. What are the types of TTL logic? :
1. Open collector output
2. Totem-Pole Output
3. Tri-state output.

18. What is depletion mode operation MOS? :
If the channel is initially doped lightly with p-type impurity a conducting channel exists at zero gate voltage and the device is said to operate in depletion mode.

19. What is enhancement mode operation of MOS? :
If the region beneath the gate is left initially uncharged the gate field must induce a channel before current can flow. Thus the gate voltage enhances the channel current and such a device is said to operate in the enhancement mode.

20. Mention the characteristics of MOS transistor? :
1. The n- channel MOS conducts when its gate- to- source voltage is positive.
2. The p- channel MOS conducts when its gate- to- source voltage is negative
3. Either type of device is turned of if its gate- to- source voltage is zero.