Electronic Interview Questions Part –
1.What is transistor?
In electronics,a transistor is a semiconductor device commonly used to amplify or switch electronic signals. The transistor is the fundamental building block of computers,and all other modern electronic devices. Some transistors are packaged individually but most are found in integrated circuits
2.What is op-amp?
An operational amplifier,often called an op-amp ,is a DC-coupled high-gain electronic voltage amplifier with differential inputs and,usually,a single output. Typically the output of the op-amp is controlled either by negative feedback,which largely determines the magnitude of its output voltage gain,or by positive feedback,which facilitates regenerative gain and oscillation.
3.What is a feedback?
Feedback is a process whereby some proportion of the output signal of a system is passed (fed back) to the input. This is often used to control the dynamic behaviour of the system.
4.Advantages of negative feedback over positive feedback.
Much attention has been given by researchers to negative feedback processes,because negative feedback processes lead systems towards equilibrium states. Positive feedback reinforces a given tendency of a system and can lead a system away from equilibrium states,possibly causing quite unexpected results.
5.What is Barkhausen criteria?
Barkhausen criteria,without which you will not know which conditions,are to be satisfied for oscillations.
“Oscillations will not be sustained if,at the oscillator frequency,the magnitude of the product of the transfer gain of the amplifier and the magnitude of the feedback factor of the feedback network ( the magnitude of the loop gain ) are less than unity”.
The condition of unity loop gain -A? = 1 is called the Barkhausen criterion. This condition implies that
A?= 1and that the phase of – A? is zero
6.What is CDMA,TDMA,FDMA?
Code division multiple access (CDMA) is a channel access method utilized by various radio communication technologies. CDMA employs spread-spectrum technology and a special coding scheme (where each transmitter is assigned a code) to allow multiple users to be multiplexed over the same physical channel. By contrast,time division multiple access (TDMA) divides access by time,while frequency-division multiple access (FDMA) divides it by frequency.
An analogy to the problem of multiple access is a room (channel) in which people wish to communicate with each other. To avoid confusion,people could take turns speaking (time division),speak at different pitches (frequency division),or speak in different directions (spatial division).
In CDMA,they would speak different languages. People speaking the same language can understand each other,but not other people. Similarly,in radio CDMA,each group of users is given a shared code. Many codes occupy the same channel,but only users associated with a particular code can understand each other.
7.explain different types of feedback
Types of feedback:
Negative feedback: This tends to reduce output (but in amplifiers,stabilizes and linearizes operation). Negative feedback feeds part of a system’s output,inverted,into the system’s input; generally with the result that fluctuations are attenuated.
Positive feedback: This tends to increase output. Positive feedback,sometimes referred to as “cumulative causation”,is a feedback loop system in which the system responds to perturbation (A perturbation means a system,is an alteration of function,induced by external or internal mechanisms) in the same direction as the perturbation. In contrast,a system that responds to the perturbation in the opposite direction is called a negative feedback system.
Bipolar feedback: which can either increase or decrease output.
8.What are the main divisions of power system?
The generating system,transmission system,and distribution system
9.What is Instrumentation Amplifier (IA) and what are all the advantages?
An instrumentation amplifier is a differential op-amp circuit providing high input impedances with ease of gain adjustment by varying a single resistor.
10.What is meant by impedance diagram.
The equivalent circuit of all the components of the power system are drawn and they are interconnected is called impedance diagram.