Operational Electronics Engineering Interview Preparation Guide

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In digital ciruit, the gate output can be only high or low. In highstate the output source current at a minimum voltage, greater than ~2.8V if load(fan out ) is proper. In low state it will sink current at max output voltage less than ~0.8V. Some times it is derirable to have a state output both not high or low. with neither sinking or sourcing (with high output impedance). This is called tristate. Tristate output cannot change output condition of succeding logic gates, unless tristate is disabled.

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Ideal OP-AMP is a power ful concept.

If one goes through the history of amplifying devices, it becomes clear that less it loads the previous stage, better the output signal. ie. it is a trend toward higher and higher input impedances.

Also it is better to maintain the signal level irrespective of the LOAD connected at the ouput. Lesser the output impedance, less the signal amplitude reduction when load is connected. ie. it is a trend toward lower and lower output impedances.

As ideal opamp is a concept , by virtue it has zero output impedance and infinite input impedance, and they are not physically measurable but has to be taken for granted for the use in theoritical analysis.

To measure input resistance, of non ideal opamp, connect a known source at the input and give a signal (within Specifications) through a current meter of sufficient precision. Input voltage by current gives the input impedance.

To measure input resistance, of non ideal opamp, connect a known source at the input and give a signal (within Specifications) through a current meter of sufficient precision. Input voltage by current gives the input impedance.

To measure output resistance, of non ideal opamp, connect a known source at the input such that the output does not saturate and connect a load (within Specifications ) through a current meter of sufficient precision and meaure the output voltage. Output voltage by current gives the output impedance.

Please refer application notes by device manufacturers freely availble in internet for more precise and practical solutions.

In any (electronic) device controlling parameter is current it is called current controlled device. eg bilpolar transistor- output current is a function of base current.

In any (electronic) device controlling parameter is voltage it is called voltage controlled device. eg Field effect transistor- output current is a function of gate voltage.

It depends on the inherent physical mechanism which defines the primary (independent) controlling parameter.

SCS is nothing but the switch (sillicon controlled switch SCR),but GTO is one of the turn off method in SCR.if any other answer for this question please forward me too the answer.

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They are two types one is forward resistance

1.Forward resistance
2.Reverse
resistance

1.Forward resistance
This is the resistance offered in forward bias condition of the diode.
It is calculated by with the help of graph for voltage and current characteristic.

2.Reverse resistance
This resistance is offered in the reverse bias condition of the diode. It is also calculated by the same method.

In a conducting material, the electrons are governed by Fermi-Dirac statistics. The baseline electron energy is the Fermi Energy*, and at low temperatures the electrons all exist at or below this level. As temperature is increased, so the distribution function for the electrons develops a high energy 'tail'. Some of these electrons have sufficient energy to pass over the surface potential barrier between the material and the vacuum. This process of increasing the temperature of a bulk material to increase the number of electrons which can leave the material is called thermionic emission or Edison effect.

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AlE stands for the address latch enable
it 's working is that it differentiate the address and data bus in microprocessor.
when it is high it select address bus .
when it is low it select data bus.

Bias current of a transistor is the preset DC current when no input voltage signal is applied to it.

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In power amplifier feedback employed is current feedback and In voltage amplifier, voltage feedback is employed.

by connecting a pmos transistor and cmos transistor in series and take the output from middle of the connection

There are basically two reasons for doing so, one is to remove GROUND BOUNCE one more reason is circuit complexity demands a large amount of current flowing through the circuits, and multiple grounds help in dissipating the accumulated heat so that device will be safe.

PLC stands for Programmable Logic ControllerDCS for Data control SystemSCADA for Supervisory Control And Data Acquisition SCADA involves supervision by a user, in most cases the plant controller.Whereas PLC is the means by which he performs the function of SCADA.DCS on the other hand stand only to control the system and not to log any datain the process of controlling.

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Binary of 1011 -
1101

Steps

1. write the msb as itseif (here retain fourth bit say 1 ) and it will be the
msb of binary.

2. add the msb of binary (say 1) with next bit of gray (say 0 ie third bit )and
the sum (1) becomes next bit of binary. note: if any carry generated just discard
it.

3. previous sum (1) is again added with next bit of gray(1 ie second bit) and
this sum(0) becomes second bit of binary .

4. previous sum (0) is again added with next bit of gray (1 ie first bit) and
the sum (1) becomes first bit of binary.

An active digital line in case of multiplexed buses has three states. high & low when controlled, and tristated when not controlled or when it is free to be used by other controller. this state where in it's level is not determinable or when it is floating is called tristate.

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BJT as current controlled device -
Base current controls the collector an emitter currents

FET as voltage controlled device-
Field of p or n region decides width of conducting channel in n type or p type FET

A xor B= A'B + AB'

hence, if A=0, then the output is B
if A=1, then the output is B'

so we need only ONE mux (2:1), which is controlled by A, and its inputs are B --> mux_in_0
B' --> mux_in_1

the h-parameter or the hybrid parameters of a transistor helps us to analyse the amplifying action of transistor for small signal .

It depends on the range. An algorithm can be used.

For a number in the range of 0 to 19 (decimal), the following algorithm can be used:

if a<10
a_BCD=a;
else if a<20
a_BCD=a+0x06;
end

for example if a=0x0E, then a_BCD=0x0E+0x06=0x14, which is the BCD representation of 0x0E.

This could be generalized for a number in the range of 0 to 99: a_BCD=a+n*0x06, where 10*n<=a<10*(n+1).

The microprocessor is the integration of a number of useful functions into a single IC package.

These functions are: The ability to execute a stored set of instructions to carry out user defined tasks. The ability to be able to access external memory chips to both read and write data from and to the memory.

Basically, a microcontroller is a device which integrates a number of the components of a microprocessor system onto a single microchip.

So a microcontroller combines onto the same microchip : The CPU core Memory (both ROM and RAM) Some parallel digital I/O Essentially, a microcontroller is obtained by integrating the key components of microprocessor,RAM, ROM, and Digital I/O onto the same chip die. Modern microcontrollers also contain a wealth of other modules such as Serial I/O, Timers, and Analogue to Digital Converters.