Tag: the operational amplifier (op-amp)

Questions Related to the operational amplifier (op-amp)

The output of a particular Op-amp increases 8V in 12s. The slew rate is .

the operational amplifier (op-amp) electronics physics properties of an ideal op-amp

  1. $90 V/\mu s$

  2. $0.67 V/\mu s$

  3. $1.5 V/\mu s$

  4. None of these

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Correct Option: B
Explanation:

Given,

$\triangle V=8V$
$\triangle t=12 s$
To find, Slew rate$=?$
Slew rate is defined as the voltage change in $\triangle V$ with respect to changing time $\triangle t$
$\therefore$ Slew rate $=\cfrac{\triangle V}{\triangle t}$
$\Rightarrow $ Slew rate$=\cfrac{8V}{12s}$
$\Rightarrow$ Slew rate$=0.666$
$\Rightarrow$ Slew Rate$\simeq 0.67$

 Which among the following amplifier circuit exhibit the output voltage in the form of phase inversion?

the operational amplifier (op-amp) electronics physics properties of an ideal op-amp

  1. Adder

  2. Substractor

  3. Integrator

  4. Differentiator

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Correct Option: A
Explanation:

In any adder circuitry of Op-amp, the output voltage must be equivalent to the summation of all input voltages where each input voltage is a multiple of constant gain factor. This circuit is usually more similar to inverting scalar type of amplifier with an exception of possessing more than one input. Therefore, output voltage of adder or summer Op-amp is phase inverted.

Referring to subtractor, integrator and differentiator amplifiers, the output voltage of subtractor deals with the difference between two input signals, while integrator generates its output voltage in terms of integral of input voltage whereas the output voltage of differentiator is proportional to change in input in accordance to time.

Which among the following are the major responsible reasons for the cause of 'Slew Rate'?

the operational amplifier (op-amp) electronics physics properties of an ideal op-amp

  1. Current limiting

  2. Saturation of internal stages due to application of high frequency & amplitude signal

  3. Both a & b

  4. None of the above

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Correct Option: C

Which among the following is also used as a buffer or an isolation amplifier?

the operational amplifier (op-amp) electronics physics properties of an ideal op-amp

  1. Inverting amplifier

  2. Non-inverting amplifier

  3. Unity Follower

  4. Emitter Follower

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Correct Option: C
Explanation:

Unity Follower circuit provides buffering or can be also used as an isolation amplifier which has a provision to obtain a gain at unity despite the requisite of any phase reversal. Emitter follower circuit is also semantic to unity follower only with an exception of gain which is in very much proximity of being absolutely equal to 1 (unity level). 

Unity Follower is supposed to be used as buffer since it becomes quite feasible to transfer the input voltage in the form of output voltage along with the prevention of load resistance from loading down to input source simultaneously. This becomes possible because the value of input resistance tends to infinity & output resistance equals to zero.

An electronic oscillator is:

the operational amplifier (op-amp) electronics physics properties of an ideal op-amp

  1. just like an alternator

  2. an amplifier with feedback

  3. nothing but an amplifer

  4. a.c. to d.c. energy converter

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Correct Option: B

The supply voltage to an opamp is +-15volts. The opamp is connected as an inverting amplifier of gain -20. The output voltage for an input voltage of 20mV is:

properties of an ideal op-amp electronics physics the operational amplifier (op-amp)

  1. -400 mV

    • 400 mV

  3. -200 mV

  4. +200 mV

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Correct Option: A
Explanation:

Voltage gain and output voltage are related by the formula $A _v=\dfrac{output \ voltage}{input \ voltage}$. Substituting the value of input voltage, we get, output voltage = - 20 x 20mV = -400 mV

The advantage of having an infinite bandwidth in an Ideal op amp is

properties of an ideal op-amp electronics physics the operational amplifier (op-amp)

  1. Signals can be amplified without attenuation

  2. Output common-mode noise voltage is zero

  3. Output voltage occurs simultaneously with input voltage changes

  4. Output can drive infinite number of device

Show answer
Correct Option: A
Explanation:

 An ideal op-amp has infinite bandwidth. Therefore, any frequency signal from 0 to $\infty$ Hz can be amplified without attenuation.

An ideal Opamp is an ideal

properties of an ideal op-amp electronics physics the operational amplifier (op-amp)

  1. Current controlled current source

  2. current controlled voltage source

  3. Voltage controlled voltage source

  4. Voltage controlled current source

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Correct Option: C
Explanation:

The ideal opamp voltage is maintained constant. It is controlled by the input voltage. Thus the output of an opamp is controlled by the source (input) voltage

The slew rate of an ideal opamp is

properties of an ideal op-amp electronics physics the operational amplifier (op-amp)

  1. Infinite

  2. Zero

  3. Half of the voltage gain

  4. 10 times the voltage gain

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Correct Option: B
Explanation:

In an ideal opamp, output follows the input instantly and hence the time delay is zero. slew rate is calculated as the ratio of change in voltage at the output to time taken for this action to take place. If time delay is zero, the slew rate will be infinite

An opamp has a supply voltage of 9V AND -9V at its power terminals. What is the maximum output voltage one can obtain by varying the voltage across the inverting and non inverting terminals 

properties of an ideal op-amp electronics physics the operational amplifier (op-amp)

  1. Greater than 9V

  2. 9V

  3. 18V

  4. Can be infinity depending on the voltage gain of the opamp

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Correct Option: B
Explanation:

maximum voltage that can obtained will be equal to the supply voltage w.r.t ground and beyond which the amplifier will saturate