Tag: the operational amplifier (op-amp)

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Questions Related to the operational amplifier (op-amp)

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

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

  1. $90 V/\mu s$

  2. $0.67 V/\mu s$

  3. $1.5 V/\mu s$

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
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$\simeq 0.67$

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

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

  1. Adder

  2. Substractor

  3. Integrator

  4. Differentiator
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Slew rate is limited by the internal current available to charge compensation capacitors and the saturation of internal stages when driven by high-frequency or high-amplitude signals.

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

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

  1. Inverting amplifier

  2. Non-inverting amplifier

  3. Unity Follower

  4. Emitter Follower
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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:

  1. -400 mV
    • 400 mV

  3. -200 mV

  4. +200 mV
Reveal answer Fill a bubble to check yourself
A Correct answer
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

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

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

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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

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

An ideal Opamp is an ideal

  1. Current controlled current source

  2. current controlled voltage source

  3. Voltage controlled voltage source

  4. Voltage controlled current source
Reveal answer Fill a bubble to check yourself
C Correct answer
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

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

The slew rate of an ideal opamp is

  1. Infinite

  2. Zero

  3. Half of the voltage gain

  4. 10 times the voltage gain
Reveal answer Fill a bubble to check yourself
B Correct answer
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

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

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 

  1. Greater than 9V

  2. 9V

  3. 18V

  4. Can be infinity depending on the voltage gain of the opamp
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

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