APPSC Electronics & Communication Engineering 15 March 2020 Question Paper with Answers Key

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APPSC Electronics & Communication Engineering 15 March 2020 Question paper with Answers Key- APPSC conducted Lecturers in Government Polytechnic Colleges (Engineering and Non-Engineering) in A.P Technical Education Service exam on 15 March 2020 FN from 10.00 AM to 12.30 PM. Here we are providing some of the questions asked in APPSC Electronics & Communication Engineering Paper.

A system with a unity grain margin and zero phase margin is?

Oscillatory

The Laplace transform of a unit step function is?

1/s

Number of bits per symbol in a 16 QAM is?

4

The transfer function of a tachometer is of the form?

Ks

……….. has the least noise immunity?

ASK

Vector Potential is a Vector?

Whose curl is equal to the magnetic flux density

An illuminated photo – diode without an external bias operates as a …….. device?

Photovoltaic

Main purpose of oxidation in the IC Fabrication process using silicon is?

Passivation

APPSC Electronics & Communication Engineering 15 March 2020 Paper

The dominant mode of any Waveguide is that of?

Lowest cutoff frequency

The maximum efficiency of AM modulation (tone modulation) is?

33%

If a zero is added in a forward path of a second order system?

Rise time will decrease

A transmission line is distortion less if?

LG=RC

The frequency range of satellite communication is?

1.GHz to 30 GHz

Light is good for telecommunication because it is?

A high – frequency carrier

If the roots of the Characteristic equation is -2j, -2j then the system is?

Stable

A System is given by x(t) = eat u(t).The system is?

Casual and unstable

 

Electronics & Communication Engineering

APPSC Electronics & Communication Engineering 15 March 2020 Questions and answers

Which modulation technique does not use past information for modulation?

Pulse code modulation

Channel capacity of a noise – free channel having M Symbols is given by?

Log M

The Z- Transform of the function unit impulse function is?

1

Which material have maximum Forbidden Band Gap?

Silica

The voltage required to forward bias a PN junction based on silicon is?

0.70 V

The number of turns of wire needed to provide a potentiometer with a resolution of 0.05% is?

2000

The wave impedance of a medium is equal to?

The wave impedance of free-space divided by the refractive index of the medium

The current flowing in a semiconductor due to the application of an external voltage DC voltage is called?

Drift current

APPSC Electronics & Communication Engineering 15 March 2020 paper with Key

Cross correlation function provides?

Measure of similarities between two signals

In a linear circuit, when the ac input is halved, the ac output?

Becomes half

……… is not a dependent electrical energy source?

Voltage source

What is the characteristic of an ideal voltage source?

It has Zero series resistance

An ideal voltage source will charge an ideal capacitor?

Instantaneously

The MOS capacitors are widely used as ……… RAM?

Dynamic

The typical forward bias voltage of an LED is?

1.6 V

For a maximum output power, the solar cell must be operated at?

The knee of V –I Characteristics

APPSC Electronics & Communication Engineering Answers Key 15 March 2020

Which logic gate is a basic comparator?

X-NOR

The diffusion Process in an IC fabrication is done by?

Heating the wafers in an atmosphere of impurities

When used as a photodetector, a photo diode should be?

Reverse biased

In a semiconductor, the holes exist in the ……. Band?

Valence

Diodes are used to clip voltages in circuits because they act as?

Voltage sources under certain bias condition

The twin well technology is usually used to fabricate?

CMOS device

One CMOS capacitance can store ……. Bit (s) of digital information?

1

How many inputs and outputs does a 1- bit magnitude comparator have?

2 inputs and 3 outputs

APPSC Electronics & Communication Engineering 15 March 2020 Full Question Paper & Key

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