MCQOPTIONS
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MCQOPTIONS
This section includes 76 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Hysteresis is desirable in a Schmitt trigger because |
| A. | energy is to be stored/discharged in parasitic capacitances |
| B. | effects of temperature variations would be compensated |
| C. | devices in the circuit should be allowed time for saturation and de-saturation |
| D. | it would prevent noise from causing false triggering |
| Answer» E. | |
| 2. |
For a voltage follower circuit using op-amp, which of the following is true |
| A. | both input and output impedance are very large |
| B. | input impedance is very large and the output impedance is very small |
| C. | input impedance is very small and output impedance very high |
| D. | both input and output impedance are very small |
| Answer» C. input impedance is very small and output impedance very high | |
| 3. |
1 for the op-amp shown in the figure, the bias currents are Ib1 = 450 nA and Ib2 = 350 nA. The values of the input bias current (IB) and the input offset current (If) are |
| A. | IB = 800 nA, If = 50 nA |
| B. | IB = 800 nA, If = 100 nA |
| C. | IB = 400 nA, If = 50 nA |
| D. | IB = 400 nA, If = 100 nA |
| Answer» E. | |
| 4. |
Directions: It consists of two statements, one labeled as the ‘Statement (I)’ and the other as ‘Statement (II)’. Examine these two statements carefully and select the answer using the codes given below:Statement (I): An ideal op amp should have infinite bandwidth.Statement (II): An ideal op amp should have infinite input resistance and zero output resistance. |
| A. | Statement (I) and Statement (II) are individually true and statement (II) is the correct explanation of statement (II) |
| B. | Statement (I) and Statement (II) are individually true but statement (II) is not the correct explanation of statement (I) |
| C. | Statement (I) is true but statement (II) is false |
| D. | Statement (I) is false but statement (II) is true |
| Answer» C. Statement (I) is true but statement (II) is false | |
| 5. |
An OPAMP RC phase shift oscillator has three pairs of R and C, where R = 33 kΩ. If the frequency of oscillation is 100 kHz, find the value of C. |
| A. | 150.28 pF |
| B. | 21.254 pF |
| C. | 19.689 pF |
| D. | 168.89 pF |
| Answer» D. 168.89 pF | |
| 6. |
For the Op-Amp circuit shown in the figure, Vo is: |
| A. | -2 V |
| B. | -1 V |
| C. | -0.5 V |
| D. | 0.5 V |
| Answer» D. 0.5 V | |
| 7. |
In a paraphase amplifier, where two amplifiers are connected in cascade, the output from second stage |
| A. | Equals signal input without change of sign |
| B. | Equals signal input with change of sign |
| C. | Does not equal to signal input and has no sign change |
| D. | Does not equal to signal input but has sign change |
| Answer» B. Equals signal input with change of sign | |
| 8. |
A special case of non-inverting amplifier in which all of the output voltage is fed back to the inverting input of the op-amp is called: |
| A. | differentiator |
| B. | integrator |
| C. | logarithmic amplifier |
| D. | voltage follower |
| Answer» E. | |
| 9. |
A differential amplifier is used in the input stage of Op-Amps to achieve very High |
| A. | Open-loop gain |
| B. | Bandwidth |
| C. | Slew rate |
| D. | CMRR |
| Answer» E. | |
| 10. |
If HPF and LPF are of first order then BPF will have a roll-off rate of? |
| A. | -40 db/decade |
| B. | -20 db/decade |
| C. | 20 db/decade |
| D. | 40 db/decade |
| Answer» C. 20 db/decade | |
| 11. |
If the bias current in the IC-741 Op-amp is IQ = 19 μA and the internal frequency compensation capacitor C1 = 30 pF, the slew rate of the op-amp will be nearly |
| A. | 1.58 V/μs |
| B. | 1.26 V/μs |
| C. | 0.93 V/μs |
| D. | 0.63 V/μs |
| Answer» E. | |
| 12. |
An operational amplifier is: |
| A. | A direct-coupled amplifier |
| B. | An indirect coupled amplifier |
| C. | An RC coupled amplifier |
| D. | A transformer coupled amplifier |
| Answer» B. An indirect coupled amplifier | |
| 13. |
In a differential amplifier, an ideal CMRR is |
| A. | Infinity |
| B. | Zero |
| C. | 1 |
| D. | -1 |
| Answer» B. Zero | |
| 14. |
For what purpose is an active load used in the collector of the difference amplifier of an Op-amp? |
| A. | To increase the output resistance |
| B. | To increase the differential gain |
| C. | To handle large signals |
| D. | To provide symmetry |
| Answer» C. To handle large signals | |
| 15. |
In the circuit shown below, the op-amp is ideal and the Zener voltage of the diode is 2.5 volts. At the input, unit step voltage is applied, i.e. vIN( |
| A. | 2.5 |
| B. | 5 |
| C. | 7.5 |
| D. | 10 |
| Answer» D. 10 | |
| 16. |
In order to ensure that the output voltage of an opamp is zero, when both its inputs are grounded |
| A. | internal negative feedback used |
| B. | an external offset balancing circuit is used at the input terminals |
| C. | the currents incident at the output node are carefully designed |
| D. | the totem-pole output transistors are designed to have exactly equal cutin voltages |
| Answer» C. the currents incident at the output node are carefully designed | |
| 17. |
In the circuit given below, what is the output voltage (Vout)? (Assume ideal opamp and the circuit is at steady state) |
| A. | 6 |
| B. | 0 |
| C. | 2 |
| D. | 4 |
| Answer» C. 2 | |
| 18. |
In the circuit shown, the op-amp has finite input impedance, infinite voltage gain, and zero input offset voltage. The output voltage Vout is |
| A. | –I2 (R1 + R2) |
| B. | I2R2 |
| C. | I1R2 |
| D. | –I1(R1 + R2) |
| Answer» D. –I1(R1 + R2) | |
| 19. |
An amplifier is used to obtain |
| A. | an increased voltage, current or power of an input signal |
| B. | alternation of the input signal |
| C. | an amplification of frequency response of a communication signal |
| D. | a distortion-less reproduction of radio signals |
| Answer» D. a distortion-less reproduction of radio signals | |
| 20. |
For op – amp circuit shown below, assume that the open loop transfer function is given by \(A = \frac{{{{10}^4}}}{{1 + {{10}^{ - 3}}s}}\) . The Bandwidth of circuit is: |
| A. | 103 |
| B. | 104 |
| C. | 105 |
| D. | 106 |
| Answer» E. | |
| 21. |
An op-amp has an open-loop gain of 105 and an open-loop upper cut-off frequency of 10 Hz. If this op-amp is connected as an amplifier with a closed loop gain of 100, then the new upper cut-off frequency is |
| A. | 10 Hz |
| B. | 100 Hz |
| C. | 10 kHz |
| D. | 100 kHz |
| Answer» D. 100 kHz | |
| 22. |
An op-amp has a differential gain of \(\rm 10^3\) and a CMRR of \(\rm 100 \ dB\). The output voltage of the amp with inputs of \(\rm 120\ μV\) and \(\rm 80\ μV\) will the |
| A. | \(\rm 26\ mV\) |
| B. | \(\rm 40\ mV\) |
| C. | \(\rm 100\ mV\) |
| D. | \(\rm 200\ mV\) |
| Answer» C. \(\rm 100\ mV\) | |
| 23. |
Determine Vo if R1 = 100 kΩ, Rf = 500 kΩ and Vi = 2 V in the circuit shown. |
| A. | −5 V |
| B. | 5 V |
| C. | -10 V |
| D. | 10 V |
| Answer» D. 10 V | |
| 24. |
A simple single Op-Amp inverting amplifier has RF = 220 kΩ and R1 = 10 kΩ. If two such stages are cascaded, find the mid-frequency gain of the cascade. |
| A. | 53.70 dB |
| B. | -53.70 dB |
| C. | -26.85 dB |
| D. | 26.85 dB |
| Answer» B. -53.70 dB | |
| 25. |
Choose the characteristics which are not related to an ideal op-amp. |
| A. | Very high gain |
| B. | Very high input impedance |
| C. | Very low CMRR |
| D. | Very low output impedance |
| Answer» D. Very low output impedance | |
| 26. |
Gain of a buffer amplifier is: |
| A. | Dependent on the circuit parameters |
| B. | Unity |
| C. | infinity |
| D. | zero |
| Answer» C. infinity | |
| 27. |
In the circuit shown below, assume that the comparators are ideal and all components have zero propagation delay. In one period of the input signal Vin = 6 sin(ωt), the fraction of the time for which the output OUT is in logic state HIGH is |
| A. | 1/12 |
| B. | 1/2 |
| C. | 2/3 |
| D. | 5/6 |
| Answer» E. | |
| 28. |
Find the voltage V0, if Vi = 0.2 V |
| A. | -6 V |
| B. | 8 V |
| C. | 6 V |
| D. | -8 V |
| Answer» D. -8 V | |
| 29. |
A voltage follower is used as1. An isolation amplifier2. A buffer amplifierWhich of the above statements is/are correct? |
| A. | 1 only |
| B. | 2 only |
| C. | Both 1 and 2 |
| D. | Neither 1 nor 2 |
| Answer» D. Neither 1 nor 2 | |
| 30. |
Output impedance of ideal OP-AMP is |
| A. | low |
| B. | high |
| C. | infinite |
| D. | zero |
| Answer» E. | |
| 31. |
Of the four characteristic given below, which are the major requirements for an instrumentation amplifier?P: High common mode rejection ratioQ: High input impedanceR: High linearityS: High output impedance |
| A. | P, Q and R only |
| B. | P and R only |
| C. | P, Q and S only |
| D. | Q, R and S only |
| Answer» B. P and R only | |
| 32. |
Find the gain of the following op-amp circuit provided the op-amp has a finite open loop gain at 104. It is also known that the following inverting op-amp circuit has feedback resistor of 100kΩ and the input resistor equal to 1kΩ with a gain of 100. |
| A. | 100 |
| B. | 99 |
| C. | 50 |
| D. | 45 |
| Answer» C. 50 | |
| 33. |
In an LPF designed using OPAMP; if positions of R & C are interchanged then ______. |
| A. | Output remains same |
| B. | The circuit becomes oscillator |
| C. | The filter becomes HPF with same cutoff frequency |
| D. | The output of circuit goes to zero |
| Answer» D. The output of circuit goes to zero | |
| 34. |
In order to balance the offset voltage of an operational amplifier, a small DC voltage is applied to input terminals where the connection is |
| A. | Series with both inverting as well as non-inverting input |
| B. | Series with non-inverting input |
| C. | Shunt with inverting input |
| D. | Shunt with non-inverting input |
| Answer» B. Series with non-inverting input | |
| 35. |
In an RC coupled amplifier, frequency response is improved with |
| A. | Lower R1 |
| B. | Higher Cc |
| C. | Less gain |
| D. | More bias |
| Answer» C. Less gain | |
| 36. |
Assume ideal op-amps. For 2V peak-to-peak sinusoidal input Vi with zero DC component, the output V0 is a |
| A. | sine wave |
| B. | square wave |
| C. | Pulse train |
| D. | Triangular wave |
| Answer» E. | |
| 37. |
An op-amp zero crossing detector is basically ______converter |
| A. | Sine to square wave |
| B. | Square to sine wave |
| C. | Sine to sine wave |
| D. | Sine to triangle wave |
| Answer» B. Square to sine wave | |
| 38. |
In the circuit shown, the need of the resistor RF is |
| A. | To increase the overall gain |
| B. | To stabilize the circuit |
| C. | To increase input impedance |
| D. | To prevent saturation |
| Answer» E. | |
| 39. |
An OPAMP has a slew rate of 100 V/msec. For a frequency of 10 MHz, the maximum value of the sine wave output voltage will be |
| A. | 100 V |
| B. | 50/π V |
| C. | 10 V |
| D. | 5 V |
| Answer» C. 10 V | |
| 40. |
A non-inverting amplifier with gain 10 is realized using an operational amplifier having open-loop gain 105. What is the feedback factor β? |
| A. | 99.99 × 10-3 |
| B. | 9.99 × 10-3 |
| C. | 10 |
| D. | 90.9 × 10-3 |
| Answer» B. 9.99 × 10-3 | |
| 41. |
Consider the circuit shown in the figure, In this circuit \(R = 1k\Omega\), and \(C = 1\mu F\). The input voltage is sinusoidal with a frequency of 50 Hz, represented as phasor with magnitude \({V_i}\) and phase angle 0 radian as shown in the figure. The output voltage is represented as a phasor with magnitude \({V_0}\) and phase angle \(\delta\) radian. What is the value of output phase angle \(\delta\) (in radian) relative to the phase angle of the input voltage? |
| A. | 0 |
| B. | \(\pi\) |
| C. | \(\frac{\pi }{2}\) |
| D. | \(- \frac{\pi }{2}\) |
| Answer» E. | |
| 42. |
In an inverting amplifier circuit built using OP-AMP, the input resistance is 10 k Ω and the feedback resistance is 240 kΩ. The closed-loop gain of the amplifier is: |
| A. | 24 |
| B. | 12 |
| C. | -12 |
| D. | -24 |
| Answer» E. | |
| 43. |
In order to generate a square wave from a sinusoidal input signal, one can use1. Schmitt trigger circuit2. Clippers and amplifiers3. Monostable multivibratorWhich of the above statements are correct? |
| A. | 1, 2 and 3 |
| B. | 1 and 2 only |
| C. | 1 and 3 only |
| D. | 2 and 3 only |
| Answer» D. 2 and 3 only | |
| 44. |
For a given operational amplifier (op-amp), if CMRR is 105 and differential gain is also 105, the common mode gain of the op-amp is: |
| A. | 1010 |
| B. | 105 |
| C. | 0 |
| D. | 1 |
| Answer» E. | |
| 45. |
In the circuit below, the light dependent resistor (LDR) receives light from the LED. The LDR has resistances of 5 kΩ and 500 Ω under dark and illuminated conditions, respectively. The LED is OFF at time t < 0. At time t < 0 s, the switch S1 is closed for 1 ms and then kept open thereafter. Assuming zero propagation delay in the devices, the LED |
| A. | turns ON when S1 is closed and remains ON after S1 is opened |
| B. | turns ON when S1 is closed and turns OFF after S1 is opened |
| C. | turns ON when S1 is closed and toggles periodically from ON to OFF after S1 is opened |
| D. | remains OFF when S1 is closed and continues to remain OFF after S1 is opened |
| Answer» B. turns ON when S1 is closed and turns OFF after S1 is opened | |
| 46. |
In differential amplifier differential gain is 20000 and CMRR is 80 dB. Find common-mode gain? (take log 10000 = 4) |
| A. | 2 |
| B. | 1 |
| C. | 0.5 |
| D. | 0 |
| Answer» B. 1 | |
| 47. |
Find the voltage V0 |
| A. | + 8V |
| B. | - 8V |
| C. | -4V |
| D. | +4V |
| Answer» B. - 8V | |
| 48. |
A 741 type OPAMP has a gain bandwidth product of 1 MHz. A non-inverting amplifier using this OPAMP and having a voltage gain of 20 dB will exhibit a -20 dB bandwidth of |
| A. | 50 kHz |
| B. | 100 kHz |
| C. | (1000/17) kHz |
| D. | (1000/7.07) kHz |
| Answer» C. (1000/17) kHz | |
| 49. |
For a first order law pass filter unity dc gain and -3db corner frequency of 2000 π rad/s, the transfer function H(jω) is |
| A. | \(\frac{1}{{1000 + j\omega }}\) |
| B. | \(\frac{1}{{1 + j1000\omega }}\) |
| C. | \(\frac{{2000\pi }}{{2000\pi + j\omega }}\) |
| D. | \(\frac{{1000\omega }}{{1 + j1000\omega }}\) |
| Answer» D. \(\frac{{1000\omega }}{{1 + j1000\omega }}\) | |
| 50. |
A sawtooth waveform is applied to a comparator as shown in the figure given below. What is the duty ratio of the waveform at Vout? |
| A. | 25% |
| B. | 50% |
| C. | 75% |
| D. | 100% |
| Answer» D. 100% | |