ANALOG ELECTRONICS VIVA & INTERVIEW QUESTIONS & ANSWERS

ANALOG ELECTRONICS  VIVA & INTERVIEW QUESTIONS & ANSWERS

Q-1 What do you mean by operational amplifier?

 Ans :  An operational amplifier is a direct- coupled, high gain amplifier used for some mathematical operation such as addition, subtraction, multiplication and integration. 

Q-2 List the ideal characteristics of an op-amp? 

Ans :   An ideal-opamp would have the following characteristics:- 1 Infinite voltage gain 2 Infinite input resistance 3 Zero o/p resistance 4 Zero o/p voltage when (i/p voltage is zero) 5 Infinite Band with 6 infinite common mode Rejection ratio 7 infinite slew rates. 

Q-3 What are the main features of Ics 741? 

Ans :   the main features of Ics 741 are:- 1 No external frequency compensation required. 2 short circuit protection. 3 offset null capability. 4 large common mode and differential voltage range 5 low power consumption 6 No latch up problem 

Q-4 What do you mean by input offset current? 

Ans :   The algebraic difference between the current in the inverting terminals is as known as Input offset current. 

Q-5 What do you mean by input offset voltage? 

Ans :  Input offset voltage that must be applied between the two input terminals of an Opamp to null the output. 

Q-6 What do you mean by input biased current? 

Ans :   Input biased current is the average of the current that flow into the inverting and Non Inverting input terminals of the op-amps. 

Q-7 What do you mean by differential input resistance? 

Ans :  Differential input resistance is the equivalent resistance that can be measured at either the inverting and non-inverting input terminal with the other terminal connected to ground. 

Q-8 What do you mean common mode rejection ratio (CMMR). 

Ans :   Common mode rejection ratio define as “it is the ratio of the differential voltage Gain to the common mode gain of an op-amp. CMMR= differential gain/ common mode gain 

Q-9 What do you mean by SVRR (supply voltage rejection ratio).

Ans :   The change in an op-amp input –offset voltage, caused by variation in supply voltage is called supply voltage rejection ratio (SVRR). 

Q-10 What do you mean by output resistance of an op-amp? 

Ans :  The output resistance is the equivalent resistance that can be measured between the Terminal of the op-amp and ground. 

Q-11 What do you mean by slew rate of an op-amp.?

Ans : Slew rate is the maximum rate of change of output voltage per unit of time.

 Q-12 What do you mean by gain band width product of an op-amp?

Ans : The gain bandwidth of an op-amp is the “bandwidth when the voltage gain is unity”. 

Q-13 What do you mean by an open loop configuration of an op-amp?

Ans : The open loop configuration of an op-amp indicate the No connection, exist between The output signal is not fed-back in any form into the input. 

Q-14 How many configuration in open-loop op-amp configuration? 

Ans : there are three open-loop op-amp configurations: 1 Differential –amplifier. 2 Inverting amplifier 3 Non- inverting amplifier 

Q-15 What do you mean by voltage follower? 

Ans : The lowest gain that can be obtained from a non-inverting amplifier with feedback Is 1. When the non-inverting amplifier is configured for unity, it is called a voltage Follower. 

Q-16 What do you mean by a comparator? 

Ans : Comparator is an open-loop op-amplifier which compares the input voltage at other one terminal to a reference voltage at other terminal and produce a voltage at their output terminal. 

Q-17 What do you mean by a zero-crossing detector? 

Ans :   Zero-detector is a comparator in which a zero reference is applied at their non-inverting terminal. Zero-crossing detector switches their output from one state to another state if the input voltage crosses the zero point. 

Q-18 What do mean by a Schmitt trigger? 

Ans : Schmitt trigger is a type of comparator which uses positive feedback. Schmitt trigger convert a sinusoidal signal to a square wave signal. 

Q-19 How many types of Schmitt trigger used? 

Ans : There are two types Schmitt trigger are used. 1. Inverting Schmitt trigger. 2. Non-inverting Schmitt trigger. 

Q-20 What do you mean by threshold voltage of Schmitt trigger? 

Ans : The input voltage of Schmitt trigger for which the Schmitt trigger changes their output is called threshold voltage. 

Q-21 What do you mean by hysteresis of Schmitt trigger? 

Ans : Hysteresis is the voltage difference between turn-on and turn-off voltage of comparator. 

Q-22 Explain the main effect of a hysteresis? 

Ans : The main effect of hysteresis are1. It improves the noise immunity. 2. It reduces the response time. 3. It reduces the false triggering. 4. When hysteresis increases then sensitivity reduce. 

Q-23 What do you mean by a voltage to frequency converter?

Ans : A device which convert an analog voltage into a pulse signal which frequency is proportional to the applied input voltage. 

Q-24 What is the function of frequency to voltage converter?

Ans : A device which convert the frequency of the input signal into a proportional output voltage. 

Q-25 What are main application of frequency to voltage converter? 

Ans :  The main applications of these are follows1. It is used to control the speed of motor. 2. It is used for rotational measurement. 3. It is used for digital to analog conversion. 

Q-26 Explain the Timer IC-555? 

Ans :  IC-555 is timer IC which is used in a stable, multivibrator, square wave generator, triangular wave generator, pulse modulator and pulse detector circuit. 

Q-27 Explain the function of phase detector? 

Ans :  The main function of phase detector is to compare the signal with feedback voltage and produce a D.C. output voltage 

Q-28 Define an Integrated circuit. 

Ans : An integrated circuit(IC) is a miniature, low cost electronic circuit consisting of active and passive components fabricated together on a single crystal of silicon. The active components are transistors and diodes and passive components are resistors and capacitors. 

Q-29 Explain the main feature of IC-723.

Ans :  The main feature of IC-723 are1. Input voltage ( 9.5 Volt-40 volt) 2. Regulated output voltage (2 to 37 v) 3. Maximum load current = 150 ma. 4. Internal power dissipation is 800 mV 

Q-30 What is function of pulse width modulator? 

Ans :  In pulse width modulator the width of the output pulse is varying according to the variation in the amplitude of modulating signal 

Q-31 What are the two important properties of SiO2? 

Ans :  1. SiO2 is an extremely hard protective coating & is unaffected by almost all reagents except by hydrochloric acid. Thus it stands against any contamination. 2. By selective etching of SiO2, diffusion of impurities through carefully defined Windows in the SiO2 can be accomplished to fabricate various components. 

Q-32 What is oxidation induced defects in semiconductor? 

Ans : 1.Stacking faults 2. Oxide isolation defects 

Q-33 What are the advantages of ICs over discrete circuits? 

Ans : 1. Minimization & hence increased equipment density. 2. Cost reduction due to batch processing. 3. Increased system reliability 4. Improved functional performance. 5. Matched devices. 6. Increased operating speeds 7. Reduction in power consumption 

Q-34 What is OPAMP? 

Ans :  An operational amplifier is a direct coupled high gain amplifier consisting of one or more differential amplifiers, followed by a level translator and an output stage. It is a versatile device that can be used to amplify ac as well as dc input signals & designed for computing mathematical functions such as addition, subtraction ,multiplication, integration & differentiation.