# Analog and Digital Electronics 5

Analog and Digital Electronics 5

Part 5: List for questions and answers of Analog & Digital Electronics

Q1. A differential amplifier

a) Is a part of an Op-amp

b) Has one input and one output

c) Has two outputs

d) (1) and (2)

Q2. When a differential amplifier is operated single-ended,…..

a) The output is grounded

b) One input is grounded and signal is applied to the other

c) Both inputs are connected together

d) The output is not inverted

Q3. In differential-mode,……

a) Opposite polarity signals are applied to the inputs

b) The gain is one

c) The outputs are of different amplitudes

d) Only one supply voltage is used

Q4. In the common mode, ……..

a) Both inputs are grounded

b) The outputs are connected together

c) An identical signal appears on both the inputs

d) The output signal are in-phase

Q5. The common-mode gain is ……..

a) Very high

b) Very low

c) Always unity

d) Unpredictable

Q6. The differential gain is ……..

a) Very high

b) Very low

c) Dependent on input voltage

Q7. If ADM = 3500 and ACM = 0.35, the CMRR is……..

a) 1225

b) 10,000

c) 80 dB

d) Both (1) and (3)

Q8. With zero volts on both inputs, an OP-amp ideally should have an output ……

a) Equal to the positive supply voltage

b) Equal to the negative supply voltage

c) Equal to zero

d) Equal to CMRR

Q9. Of the values listed, the most realistic value for open-loop voltage gain of an OP-amp is …..

a) 1

b) 2000

c) 80 dB

d) 100,000

Q10. A certain OP-amp has bias currents of 50 uA. The input offset current is ……

a) 700 nA

b) 99.3 ?A

c) 49.7 ?A

d) none of these

Q11. The output of a particular Op-amp increases 8V in 12us. The slew rate is ……

a) 90 V/us

b) 0.67 V/us

c) 1.5 V/us

d) none of these

Q12. For an Op-amp with negative feedback, the output is ……

a) Equal to the input

b) Increased

c) Fed back to the inverting input

d) Fed back to the non inverting input

Q13. The use of negative feedback ……

a) Reduces the voltage gain of an Op-amp

b) Makes the Op-amp oscillate

c) Makes linear operation possible

Q14. Negative feedback ……

a) Increases the input and output impedances

b) Increases the input impedance and bandwidth

c) Decreases the output impedance and bandwidth

d) Does not affect impedance or bandwidth

Q15. A certain non inverting amplifier has Ri of 1 k ohm and Rf of 100 k ohm. The closed-loop voltage gain is ……

a) 100,000

b) 1000

c) 101

d) 100

Q16. If the feedback resistor is open, the voltage gain ……

a) Increases

b) Decreases

c) Is not affected

d) Depends on Ri

Q17. A certain inverting amplifier has a closed-loop voltage gain of 25. The Op-amp has an open-loop voltage gain of 100,000. If an Op-amp with an open-loop voltage gain of 200,000 is substituted in the arrangement, the closed-loop gain ……

a) Doubles

b) Drops to 12.5

c) Remains at 25

d) Increases slightly

Q18. A voltage follower……

a) Has a voltage gain of 1

b) Is noninverting

c) Has no feedback resistor

d) Has all of these

Q19. The Op-amp can amplify

a) A.C. signals only

b) D.C. signals only

c) Both a.c. and d.c. signals

d) Neither d.c. nor a.c. signals

Q20. The input offset current equals the ……

a) Difference between two base currents

b) Average of two base currents

c) Collector current divided by current gain

d) None of these

Part 5: List for questions and answers of Analog & Digital Electronics