Name of the College : Noorul Islam College of Engineering
University : Anna University
Degree : B.E
Department : Computer Science and Engineering
Subject Code/Name : CS 1202 – Electronics Circuits & Digital System
Year : II
Semester : III
Document Type : Question Bank
Website : niceindia.com
Download :https://www.pdfquestion.in/uploads/ni…AL_SYSTEMS.pdf
NICE Electronics Circuits & Digital System Question Paper
1. What is depletion region in PN junction? :
The region around the junction from which the mobile charge carriers (electrons and holes) are depleted is called as depletion region. Since this region has immobile ions, which are electrically charged, the depletion region is also known as space charge region.
Related : Noorul Islam College of Engineering IT1252 Digital Signal Processing B.E Question Bank : www.pdfquestion.in/2920.html
2. Give the other names of depletion region? :
i. space charge region
ii. Transition region
3. What is barrier potential? :
Because of the oppositely charged ions present on both sides of PN junction an electric= potential is established across the junction even without any external voltage source which is termed as barrier potential.
4. What is meant by biasing a PN junction? :
Connecting a PN junction to an external voltage source is biasing a PN junction.
5. What are the types of biasing a PN junction? :
1. Forward bias 2. Reverse bias.
6. What is forward bias and reverse bias in a PN junction? :
When positive terminal of the external supply is connected to P region and negative terminal to N region, the PN junction is said to be forward biased. Under forward biased condition the PN region offers a very low resistance and a large amount of current flows through it.
7. What is reverse bias in a PN junction? :
When positive terminal of the external supply is connected to N type and negative terminal to P type then the PN junction is said to be in reverse bias. Under reverse biased condition the PN region offers a very high resistance and a small amount of current flows through it.
8. What is Reverse saturation current? :
The current due to the minority carriers in reverse bias is said to be reverse saturation current. This current is independent of the value of the reverse bias voltage.
9. Why contact differences of potential exist in PN junction? :
When a PN junction is formed by placing a p-type and n-type material in intimate contact, the Fermi level throughout the newly formed specimen is not constant at equilibrium. There will be transfer of electron and energy until Fermi levels in the two sides did line up. But the valence and conduction band in p side cannot be at the at the same level as in n side .this shift in energy level results in contact difference of potential.
10. Give the expression of contact difference of potential? :
E0 = kT ln ND NA / ni
Where
E0 – contact difference of potential
K – Boltzmann constant
T – Temperature
ND – concentration of donor atoms
NA – concentration of acceptor atoms
ni – intrinsic concentration
11. What is the static resistance of a diode? :
Static resistance R of a diode can be defined as the ratio of voltage V across the diode to the current flowing through the diode. R = V/ I
Where
R – Static resistance of a diode
V – Voltage across the diode
I – current across the diode
12. Define dynamic resistance.
Dynamic resistance of a diode can be defined as the ratio of change in voltage across the diode to the change in current through the diode. r = V / I
Where
r – Dynamic resistance of a diode
V – change in voltage across the diode
I – change in current through the diode
13. What is an amplifier? :
An amplifier is a device which produces a large electrical output of similar Characteristics to that of the input parameters.
14. Why do we choose q point at the center of the load line? :
The operating point of a transistor is kept fixed usually at the center of the active region in order that the input signal is well amplified. If the point is fixed in the saturation region or the cut off region the positive and negative half cycle gets clipped off respectively.
15. When does a transistor act as a switch? :
The transistor acts as a switch when it is operated at either cutoff region or saturation region.