# MCQ in Electronic Circuits Part 7 | ECE Board Exam

(Last Updated On: August 7, 2018)

This is the Multiples Choice Questions Part 7 of the Series in Electronic (Audio/RF) Circuit/Analysis/Design as one of the Electronics Engineering topic. In Preparation for the ECE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including but not limited to past Board Exam Questions in Electronics Engineering field, Electronics Books, Journals and other Electronics References.

### MCQ Topic Outline included in ECE Board Exam Syllabi

• MCQ in Amplifiers
• MCQ in Oscillators
• MCQ in Rectifier
• MCQ in Filters
• MCQ in Voltage Regulation

### Continue Practice Exam Test Questions Part 7 of the Series

Choose the letter of the best answer in each questions.

301. It is a very high-gain differential amplifier with very high input impedance and very low output impedance.

A. par-amp

B. op-amp

C. differential amp

D. complementary amp

Solution:

302. What are the possible applications of operational amplifiers (op-amps)?

A. ac and dc-amplifiers

B. oscillators and signal conditioning

C. voltage-level detectors and comparators

D. all of the above

Solution:

303. An operational amplifier must have at least how many usable terminals?

A. 3 terminals

B. 5 terminals

C. 8 terminals

D. 14 terminals

Solution:

304. The circuit at the input stage of operational amplifiers

A. differential amplifier

C. current mirror

D. complementary amplifier

Solution:

305. An amplifier whose output is proportional to the difference between the voltages applied to its two inputs.

A. differential amplifier

B. differencing

C. delta amp

D. cascode-amp

Solution:

306. In op-amps functional block diagram, what follows the differential amplifier?

A. cascode-amplifier

B. complementary amplifier

C. level shifter

D. high gain amplifier

Solution:

307. A good op-amp has a

A. very high input resistance

B. very low input resistance

C. very high output resistance

D. very low CMRR

Solution:

308. Ideally, op-amps have infinite input resistance and ________ output resistance.

A. infinite

B. zero

C. variable

D. a highly stabilized

Solution:

309. How does the input of an op-amp made high?

A. by using super beta transistor at the input differential stage

B. by using FETs at the input differential stage

C. by connecting a very high resistance in series with the input differential stage

D. A and B above

Solution:

310. What type of amplifier commonly used at the output stage of op-amps?

A. differential amplifier

C. complementary amplifier

D. darlington stage amplifier

Solution:

311. The transistor configuration used at the output complementary stage of most op-amps

A. cascode configuration

B. common emitter

C. common collector

D. common base

Solution:

312. Why do most op-amps use a common collector at the output stage?

A. to have a higher output power

B. to have a better frequency response

C. to have a low harmonic distortion

D. to have a very low output resistance

Solution:

313. The stage followed by the output complementary in op-amps functional block diagram.

A. level shifter

B. phase shifter

C. current mirror

D. polarizer

Solution:

314. What is the purpose of a level shifter in op-amps?

A. to set and/or adjust the output voltage to zero when the input signal is zero

B. to set and/or adjust the input offset voltage to zero

C. to shift the input offset current to zero

D. all of the above

Solution:

315. Primarily, op-amps are operated with bipolar power supply, however, we can also use single polarity power supply by

A. generating a reference voltage above ground.

B. “floating” the negative supply terminal (V-) of the op-amp.

C. simply connecting the negative supply terminal (V-) of the op-amp to ground.

D. isolating the negative supply terminal (V-) by a capacitor.

Solution:

316. Op-amps have two input terminals namely, the inverting (-) and non-inverting (+) inputs. What is the significance of its name?

A. If a sine-wave is applied to the inverting (-) input, the output will be inverted or shifted by 180°, while if applied to the non-inverting (+) there will be no phase shift at the output.

B. If pulses are applied to the inverting (-) input, the positive pulse becomes negative at the output and vice versa, while if applied at the non-inverting (+) there will be no reversal of the pulse at the output.

C. In dc amplifier applications, increasing input at the inverting (-) terminal causes the output to decrease and vice versa, while at the non-inverting (+) input, the output magnitude goes with the input.

D. all of these are correct

Solution:

317. When the same signal is applied to both inverting and non-inverting input terminals of an ideal op-amp, the output voltage would be

A. zero (0) V

B. +VSAT

C. –VSAT

D. offset voltage

Solution:

318. The operating mode of an op-amp, when both inputs are tied together or when the input signal is common to both inputs.

A. differential mode

B. rejection mode

C. double-ended mode

D. common mode

Solution:

319. What do you call of the gain of an op-amp if operated in common mode input?

A. differential gain

B. common gain

C. double-ended gain

D. rejection gain

Solution:

320. When one input of the op-amp is connected to ground and the other is to the signal source, its operation is called

A. single-ended output

B. double-ended output

C. single-ended input

D. double-ended input

Solution:

321. If op-amps are operated in differential mode, its gain is technically termed as

A. common-mode differential gain

B. differential gain

C. open-loop gain

D. closed-loop gain

Solution:

322. In op-amps, which gain is the highest?

A. common-mode gain

B. differential gain

C. closed-loop gain

D. open-loop gain

Solution:

323. The ratio of the differential gain and common gain of an op-amp

A. differential-common mode ratio

B. common-mode ratio

C. differential-mode rejection ratio

D. common-mode rejection ratio

Solution:

324. An operational amplifier has a common-mode voltage gain of 10 and a differential-mode voltage gain of 20,000, calculate its common-mode rejection ratio (CMRR).

A. 200

B. 2,000

C. 20,000

D. 200,000

Solution:

325. Calculate the CMRR of an op-amp having a common-mode gain of 10 and a differential-mode gain of 100,000.

A. 1000 dB

B. 100 dB

C. 80 dB

D. 40 dB

Solution:

326. The non-inverting and inverting inputs of an op-amp have an input voltage of 1.5 mV and 1.0 mV, respectively. If the op-amp has a common-mode voltage gain of 10 and a differential-mode gain of 10,000, what is its output voltage?

A. 5.0 V

B. 5.0125 mV

C. 5.0125 V

D. 25.0125 V

Solution:

327. What is the maximum output voltage swing of an op-amp?

A. +V to -V (supply voltage)

B. +VSAT to -VSAT

C. +½V to -½V

D. depends on the input signal

Solution:

328. The µA741 op-amp has a CMRR of 90dB and a differential-mode voltage amplification of 200,000.What is the op-amp’s common-mode voltage gain?

A. 31,622.778

B. 632.40

C. 6.324

D. 0.158

Solution:

329. The current needed at the input of an op-amp to operate it normally

A. input bias current

B. input offset current

C. input threshold current

D. input holding current

Solution:

330. Ideal op-amp requires no input current, but real op-amp needs a very small input current called input bias current. At both inputs, the bias currents have a slight difference. What do you call this difference?

A. differential input current

B. differential bias

C. input offset difference

D. input offset current

Solution:

331. The change in input offset current due to temperature change

A. delta input offset current

B. slew rate

C. input offset current drift

D. PSRR

Solution:

332. The reason why a slight difference between the input bias current occurs in op-amps is due to the unsymmetrical circuit component parameters. This unsymmetrical condition also produces a difference in input voltage called what?

A. drift voltage

B. differential voltage

C. input offset voltage

D. input threshold voltage

Solution:

333. As electronic circuit operates, its operating temperature changes which causes device parameters to change. In op-amps, what do you call the change in input offset voltage due to the change in temperature?

A. input differential drift

B. input offset voltage drift

C. slew rate

D. PSRR

Solution:

334. It is known through experiment that the input bias currents at the non-inverting (IB+) and inverting (IB-) inputs of a certain op-amp is 100 nA and 80 nA, respectively. Determine the op-amp’s input offset current.

A. -20 nA

B. 20 nA

C. 90 nA

D. 180 nA

Solution:

335. Ideally, the output voltage of an op-amp is zero when there is no input signal, however, in practical circuits, a small output voltage appears, this voltage is known as

A. minimum output voltage

B. pinch-off voltage

C. output offset voltage

D. saturation voltage

Solution:

336. The output offset voltage of an op-amp is (are) due to

A. input offset current

B. input offset voltage

C. voltage and current drift

D. A and B above

Solution:

337. Calculate the output offset voltage of an inverting amplifier using op-amp with an input offset current of 10 nA. The circuit is having an input resistance of 10 kΩ and a feedback resistance of 100 kΩ.

A. 0.1 mV

B. 1.0 mV

C. 10.0 mV

D. 100.0 mV

Solution:

338. An op-amp inverting amplifier uses a feedback resistor of 100 kΩ and input resistor of 10 kΩ. If the op-amps input offset voltage is 2.0 mV, approximate the amplifier output offset voltage due to this input offset voltage.

A. 10 mV

B. 11 mV

C. 20 mV

D. 22 mV

Solution:

339. The output offset voltage of an op-amp is due to the input offset current and voltage. If 1 mV is due to the input offset current and 22 mV due to the input offset voltage, what is the total output offset voltage of the op-amp?

A. 11.5 mV

B. 22 mV

C. 23 mV

D. 45 mV

Solution:

340. How will you minimize the output offset voltage due to the input offset current of an op-amp?

A. by installing a bias-current-compensating resistor

B. by increasing the value of the feedback resistor

C. by decreasing the value of the input resistor

D. B and C above

Solution:

341. What is a bias-current compensating resistor in op-amp circuits?

A. A resistor used to reduce the undesired output offset voltage due to the input offset current.

B. A resistor connected between the non-inverting terminal and ground.

C. A resistor used to balance both input bias currents and therefore eliminates the input offset current.

D. all of these

Solution:

342. The approximate value of the bias-current compensating resistor in op-amp circuits is

A. equal to the feedback resistor

B. equal to the input resistor

C. equal to the series combination of the input and feedback resistors

D. equal to the parallel combination of the input and feedback resistors

Solution:

343. In op-amp analysis, the input offset voltage is represented by

A. a battery

B. a signal generator

C. Thevenin’s voltage source

D. Norton’s current source

Solution:

344. The battery representing the input offset voltage in op-amp circuit analysis is connected where?

A. between the inverting and ground terminal

B. between the non-inverting and ground terminal

C. between the inverting and non-inverting terminal

D. either B and C above

Solution:

345. What is the effect of the input offset voltage to the output voltage if the op-amp has no feedback element?

A. causes the output to be always at cutoff

B. causes the output to saturate towards positive

C. causes the output to saturate towards negative

D. causes the output to saturate either towards positive or negative

Solution:

346. How can we minimize the effect of the input offset current and input offset voltage at the output offset voltage?

A. by making the feedback resistance small

B. by making the feedback resistance large

C. by making the input resistance small

D. by making the input resistance large

Solution:

347. An op-amp is wired as an inverting amplifier with an input and feedback resistances of 1 kΩ and 100 kΩ, respectively. When the input signal is set to zero, the output was found to have an offset voltage of 101 mV. Calculate the input offset voltage.

A. 0.01 mV

B. 0.1 mV

C. 1.0 mV

D. 10.0 mV

Solution:

348. What is the most effective way of minimizing the output offset voltage of an op-amp?

A. by reducing the value of the feedback resistor

B. by increasing the value of the input resistor

C. by a capacitor-compensation technique

D. by properly using and adjusting the offset-null terminals

Solution:

349. What cause(s) the well-adjusted output offset voltage of op-amps to change?

A. change in operating temperature

B. component aging

C. variations in supply voltage

D. all of the above

Solution:

350. Which op-amp parameter(s) that normally affects its small signal dc-amplification performance?

A. input bias current

B. input offset voltage

C. input offset current

D. all of the above

Solution:

### Questions and Answers in Electronic Circuits

Following is the list of practice exam test questions in this brand new series:

MCQ in Electronic Circuits
PART 1: MCQs from Number 1 – 50                        Answer key: PART 1
PART 2: MCQs from Number 51 – 100                   Answer key: PART 2
PART 3: MCQs from Number 101 – 150                 Answer key: PART 3
PART 4: MCQs from Number 151 – 200                 Answer key: PART 4
PART 5: MCQs from Number 201 – 250                 Answer key: PART 5
PART 6: MCQs from Number 251 – 300                 Answer key: included
PART 7: MCQs from Number 301 – 350                 Answer key: included
PART 8: MCQs from Number 351 – 400                 Answer key: included
PART 9: MCQs from Number 401 – 415                 Answer key: included

### Complete List of MCQ in Electronics Engineering per topic

MCQ in Electronic Circuits Part 7 | ECE Board Exam
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