Analog Electronics Circuit MCQ PDF 18ECE201J SRM university Chennai PDF

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UNIT-4 (MCO)

1. Efficiency of Class AB Amplifier A) 25 to 30% B)70 to 80% C) Better than Class A but less than Class B D)Higher than 80% 2. Which power amplifier is used for switching design? A) Class A B) Class B C) ClassC D 3. If the output power is 50W and average DC power required from power supply is 200W then the efficiency of Class A amplifier? A) 0.25 B)O.50 C)0.75 D)l.o

the

4. A transformer coupled Class A power amplifier has a load of IOOQ on the secondary. If the turn ratio is 10: 1, what is the value of load appearing on the primary? A) 5KQ B)20KQ C)IOOKQ D)IOKO 5. What will be the collector efficiency of a power amplifier having zero signal power dissipation of 5W and a. c power output of 2W?

6. If the zero signal dissipation of a transistor is IW ,then the power rating of the transistor should be atleast A) 2W B)IW C)5W D)it damages 7. The operating cycle of Class AB Amplifier A) 3600 B)1800 C)1800 to 3600 D)Less than 1800 8. Cross Over Distortion occurs in A) Class A B) Class B C)C1ass C D)C1ass AB 9. The conversion efficiency of a class C amplifier is A) 50% B)Larger than 78.5% C) 78.5% D) Lesser than 78.5% 10.1n Class B amplifier, Q-Point is located at A) Cut-off B)Saturation C)At the middle of load line D)At active region 11 .Categorize the power efficiency of each class of amplifier, from worst to best.

12. Which of the following classes of amplifiers is most suited for making tuned amplifiers? A) Class A B)C1ass B C)C1ass C D)Class D 13. A power amplifier is limited to use at one fixed frequency. A) Class A B)C1ass B C)C1ass C D)C1ass D 14.Calculate the efficiency of a transformer-coupled class A amplifier for a supply of 15 V and an output of V(p) = 10 V. A) 25%

15. Which class of amplifier operates in the linear region for only a small part of the input cycle? A) A B)AB 16.High power efficiency of the push-pull amplifier is due to the fact A) Each transistor conducts on different cycles of the input. B) Transistors are placed in CE configuration. C) There is almost no quiescent collector current D) Low forward biasing voltage is required. 17. The efficiency of class B push-pull amplifiers is much higher than that of class — A amplifiers primarily because A) The distortion is kept within acceptable limits B) One half of the input signal is amplified using one transistor and the other half is phase inverted and fed to the other transistor. C) Matched pair of transistors are used in the class B push-pull operation. D) The quiescent dc current is avoided. 18.1n a class C amplifier A) Efficiency and distortion both are maximum B) Efficiency and distortion both are minimum. C) Efficiency maximum but distortion minimum. D) Efficiency minimum but distortion maximum 19.A push-pull amplifier uses dc supply, Vcc = 30V which is equally shared between two transistors. If saturated collector current in each transistor is 40A, the maximum ac power available than the amplifier is close to

A) now B)60W C)30W D)0W 20.The complementary Darlington-connected transistor for a class B amplifier provides output current and output resistance. A) Higher, Higher B)Lower, Higher C)Lower, Lower D)Higher, Lower 21.Which of the push-pull amplifiers is presently the most popular form of the class B power amplifier? A) Quasi-complementary B) Transformer-coupled C) Complementary-symmetry D) Series-Fed 22.The maximum a.c. power output from a class B power amplifier is 10 W. What should be the minimum power rating of the transistor used? A) 20W B)2W C)10W D)4W 23.The Power amplifiers generally use transformer coupling because the transformer permits A) Cooling of the circuit B) Impedance Matching C) Distortion less Output D) Good Frequency Response 24.Which one of the following statements is not correct about class A power amplifiers A) The amplifier dissipates / wastes half the power when no input signal is there B) The efficiency can be almost doubled using transformer coupled load

C) The distortion in the output signal is high D) The transistor should be able to dissipate double of ac power of the amplifier. 25. Why filters are required in class D amplifier?

A) Output is completely dependent on the lower frequency spectrum B) To increase the complexity C) To obtain only lower frequency D) To nullify noise

26.A heat sink is generally used with a transistor to A) increase the forward current B) decrease the forward current C) compensate for excessive doping

D) prevent excessive temperature rise

UNIT-5 IC BIASING &LIFIERS WITH ACTIVE LOAD PART-A (MCQ) 1) Current Mirror is a A) Constant Voltage Source B) Unstable Voltage Source B) Constant Current Source D) Unstable Current Source 2) The relationship between IREF and 10 in two transistor current source is and IREF=O.62mA, the load current

3) For 10 is

A) 1.2mA B)2mA C)O.42mA D)O.60mA 4) If lo=1001..1A and output resistance of two transistor current source is A) IMO B)IKQ C)IOKQ D)O.IMQ 5) Which of the following current sources limits the IC resistor values to low kilo ohm range? A) Wilson Current Source C) Wildar Current Source B) Cascade Current Source D)Both Cascade and Wilson Current Sources 6) Buffered current mirror is a A) Two-Transistor Current source B) Three-transistor Current source B) Wilson Current source D) Wildar Current Source 7) The increased Ro of the Wilson Current Source is due to A) Negative Feedback C)Positive Feedback B) Cascade configuration D) Stable Bias Current 8) A Wildar current source has A) Generates high current C) Low output resistance B) Generates low current due to emitter degeneration resistor D)Both (B) and (C) 9) Which current source exhibits a very high output resistance? A) Cascade Current Mirror B)Wilson Current Mirror

B) Wildar Current Mirror D)Simple Current Mirror 10) Multi transistor current mirror is also referred as A) Active Repeater B)Buffered Current Mirror C)Current Repeater D) Load Repeater 11) If transistors are identical in 3-transistor current mirror then output current is 12) The Cascade current Source increases the output resistance by a factor of D) 2/ß 2

2

13) 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

14) The common-mode gain is ........... A) Very high

B) very low

C) always unity D) unpredictable

15) The differential gain is A) very high B)very low C)dependent on input voltage D)About 100

16) The ability of a differential amplifier to reject a common mode signal is A) Differential Mode gain B) Common mode rejection ratio C) Common Mode Gain

D) Differential mode rejection ratio

17) The BJT differential pair has Ad-IOO and ACM=O.IO. The CMRR is A) 10 B) 100 C) 0.01 D) 1000

18) The open circuit differential mode voltage gain for a differential amplifier with an active load is

A) Small B) Large C) Equal to Unity D) Infinite 19) The differential mode gain of BJT differential amplifier with gm=15.38mA/V and Rc --12KQ is (one sided output) A) 46.15 B) 184.6 C) 92.28 D) 138.45 20)gives a constant current. A) High output resistance B) Low output resistance C)Zero output resistance D) High input resistance

21) The DC transfer characteristics of BJT and MOSFET differential pair are A) Linear B) Non linear C) Active D) Negligible 22) The Common-mode rejection ratio is A) Low B) Expressed in decibels C) Equal to voltage gain D) Negative 23) A common-mode signal is applied to A) Non-inverting input B) Inverting Input C) both inputs D) None 24) A BJT Differential pair operates in linear region when A) VDVT 25) DC coupled differential amplifier is also known as A) Source coupled amplifiers B) Emitter coupled amplifiers C) BJT differential amplifier D) Both (B) and (C)

ANALOG ELECTRONICS CIRCUITS (18ECC21 W) UNIT 4

1. Efficiency of Class AB Amplifier A) 25 to

B)70 to

C) Better than Class A but less than Class B D)Higher than 80% 2. Which power amplifier is used for switching design?

A) Class A B) Class B C) Class C D)Class D 3. If the output power is 50W and average DC power required from the power supply is 200W then the efficiency of Class A amplifier? A) 0.25 B)o.50 C)O.75 D)l.o

4. A transformer coupled Class A power amplifier has a load of I OOQ on the secondary. If the turn ratio is 10: 1, what is the value of load appearing on the primary? A) 5KQ B)20KQ C)IOOKQ D)IOKQ

5. What will be the collector efficiency of a power amplifier having zero signal power dissipation of 5W and a. c power output of 2W?

6. In Class B amplifier, Q-Point is located at A) Cut-off B)Saturation C)At the middle of load line D)At active region 7. Categorize the power efficiency of each class of amplifier, from worst to best. 8. Which of the following classes of amplifiers is most suited for making tuned amplifiers?

A) Class A B)Class B C)Class C D)Class D power amplifier is limited to use at one fixed frequency.

A) Class A B)Class B C)Class C D)Class D 10. Calculate the efficiency of a transformer-coupled class A amplifier for a supply of 15 V and an output of V(p) = 10 V. A) 25% 1 1. Which class of amplifier operates in the linear region for only a small part of the input cycle?

A) A B)AB 12. The complementary Darlington-connected transistor for a class B amplifier provides

resistance.

output current and

output

A)

Higher, Higher B)Lower, Higher C)Lower, Lower D)Higher, Lower

13. Which of the push-pull amplifiers is presently the most popular form of the class B power amplifier? A) Quasi-complementary B) Transformer-coupled C) Complementary-symmetry D) Series-Fed

14. The maximum a.c. power output from a class B power amplifier is 10 w. What should be the minimum power rating of the transistor used? A) B)2W c)10W D)4W 1 5. The Power amplifiers generally use transformer coupling because the transformer permits A) Cooling of the circuit B) Impedance Matching C) Distortion less Output D) Good Frequency Response

16. Which one of the following statements is not correct about class A power amplifiers A) The amplifier dissipates / wastes half the power when no input signal is there

B) The efficiency can be almost doubled using transformer coupled load C) The distortion in the output signal is high D) The transistor should be able to dissipate double of ac power of the amplifier.

17. Why filters are required in class D amplifier? A) Output is completely dependent on the lower frequency spectrum B) To increase the complexity C) To obtain only lower frequency

D)

To nullify noise

1 8. For class A power amplifier zero signal power dissipation of 20W and AC output power is 5W, the collector efficiency is 50% 25%

68.5% 19. If single stage class A amplifier has Vcc = 20 volt, VCEQ = 10 volt, ICQ = 600 mA and collector load resistor RL = 1 6Q, what is the DC power delivered to the transistor?

a. 3.2 w

c. 4.5 w d. 6.24 w 20. A single transistor is operating as an ideal class B amplifier with 1 kQ load and a load current of 10mA. What is the power delivered to the load?

a. 0.5 w

b. 0.1 W c. 0.2 w d. 0.3 w 21 . If class B power amplifier providing 20 V peak signal tol 6Q load and a power supply of Vcc = 30 V.What is the input power?

a. 13.5 w b. 14.3 w c. 26.5 w d. 11.9 W 22. Which of these is incorrect for complementary symmetry push-pull amplifiers? a. During positive cycle NPN transistor conducts

b. It is easier to fabricate on IC c. Size of the transformer required reduces d. Efficiency and figure of merit are same as transformer coupled 23.

push-pull amplifier A power transistor has thermal resistance e = 3000C/W. if the maximum junction temperature is 900C and the ambient temperature is 300C, what is the maximum permissible power dissipation?

a. 300 mW b. 1000 rnW c. 500 mW d. 200 mW 24. A class B amplifier uses Vcc = IOV and drives a load of IOQ. What is the end point values(lC(sat), VCE(off)) of the AC load line? a. 500mA and 5V b. 200mA and 6V c. 300mA and 2V d. 400mA and 3V 25. Choose the characteristics of Class - C Amplifier a. The biasing of transistor must below cut-off b. The output signal will not resembles the input signal

c. The overall efficiency is nearly 100% d. Class C amplifier is low efficient amplifier 26.

Why do we use CE amplifier as a large signal class a amplifier?

a) It has very high output impedance b) It has very high input impedance

c) It has very high voltage gain d) It is very much stable 27. Which of the following technique is used to increase the efficiency of class A amplifier?

a) By using FET b) By using PNP transistor c) By using matched transformers as load d) By using potentiometers as load 28. What is the conduction angle of class A amplifier?

a) 90 b) 180 c) 270

d) 360 29. Where does the Q point lie for class B amplifier? a) Active

b) Cut off c) Saturation d) Between saturation and active

30.

What happens when class B amplifier is in a quiescent state?

a) No current flows through the transistor b) Maximum current flows through the transistor c) Half of the maximum current flows through the transistor d) Quarter of the maximum current flows

31.

Which is the main disadvantage of class B amplifiers? a) Expensive b) Less efficient c) More power dissipation d) More heat dissipation

32.

How to avoid cross over distortion? a) By using more resistance b) By using more capacitance c) By using more Inductance d) By shifting the Q point above cut off

UNIT -5 1) Current Mirror is a A) Constant Voltage Source B) Unstable Voltage Source B) Constant Current Source

D) Unstable Current Source

2) The relationship between IREF and 10 in two transistor current source is

3) For BJT, two transistor current source of values ßl=ßF75 and IREF=0.62mA, the load current 10 is

A) 1.2mA B)2mA C)O.42mA D)O.60mA 4) If IREF 10=1 00pA and Å=O.OIV l ,the output resistance of two transistor current source is

B)IKQ C)IOKQ D)O.IMQ

5) Which of the following current sources limits the IC resistor values to low kilo ohm range?

A) Wilson Current Source C) Wildar Current Source B) Cascade Current Source D)Both Cascade and Wilson Current Sources 6) If transistors are identical in 3-transistor current mirror then output current isß

12) 2 7) The Cascade current Source increases the output resistance by a factor of 2 c)

2

D) 2/ß

2 8) 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 9) The common-mode gain is A) Very high B) very low C) always unity D) unpredictable 1 0) The differential gain is A) very high B)very low C)dependent on input voltage D)About 100 1 1) The DC transfer characteristics of BJT and MOSFET differential pair are A) Linear B) Non linear C) Active D) Negligible 1 2) The Common-mode rejection ratio is

A) Low B) Expressed in decibels C) Equal to voltage gain D) Negative 13)

A common-mode signal is applied to A) Non-inverting input B) Inverting Input C) both inputs D) None 14) A BJT Differential pair operates in linear region when

A) VDVT

C) VD=O D) VT-O

1 5) DC coupled differential amplifier is also known as A)Source coupled amplifiers B) Emitter coupled amplifiers C) BJT differential amplifier

D) Both (B) and (C) 1 6) What will be the reference current for the two transistor current source with circuit parameters VCC = 10 V, RI = 15 kQ? The transistor parameters are VBE = 0.7 V,

$100

a. b. c. d.

0.62 mA 0.5 mA 0.25 mA 0.1 mA

1 7) What will be the output current for the two transistor current source with circuit parameters Vcc= 10 V, RI = 15 kQ? The transistor parameters are VBE = 0.7 V, ß=100 a. 0.62 mA b. 0.456 mA c. 0.608 rnA

d. 0.1 mA 1 8) What will be the mirrored current I of the two transistor current source? If RI -- 25 kQ and vcc = 12 V? a. 0.263 mA b. 0.987 mA

c. 0.452 mA d. 0.223 1 9) What would be the Ro value for the cascade current source? a. b. c. d.

ßr04

2ßr04 ß/r04 2ß/r04

20) What would be the approximate Ro value for the Wilson current source? a. 2ßr03 b. 2ßr03/6 c. ßr03 /4 d. ßr03/2 21) For multi transistor current source output current 10 is given by

c. 22) For the Widlar current source, what is trans conductance (gm2)? The parameters are: V + = 5 V, V -5 V, RI = 9.3 kQ , and 9.58 kQ . Let VA: 80 V and ß = 100. 12 PA, VT = 0.026 V.

a. 0.362 mA/V b. 0.562 mA/V c. 0.462 mA/V d. 0.262 mA/V 23) What is the output resistance(Ro) for the MOSFET Wilson Current source? gml /rol r03 b. gml +r01+r03 C. gm1r01r03 d. gml -rol-r03

24) For the Wilson circuit shown below determine the output current (l ). Assume vcc = 20V , = o.7V, VT = 26mV, vA = 150V and ß = 150. +Vcc

Q2

a) 10.23mA

b) 1.23mA

c) 5.27mA d) 4.25mA 25) In a differential amplifier if VI =2+0.005sinwt and VFO.5-0.005sinwt, then what will the value of Vcm

c) 1.25V

d) 2.5V

26) Determine the Common mode rejection ratio of a BJT based differential pair with differential mode gain to be 120.1 and common mode gain to be +0.257 a) 135.32 b) 461.37 c) 467.37 d) 450.24 27) Determine the output Resistance (FRO) of the MOSFET differential amplifier with the parameters X=O.01 VI , Kn=l mA/V2, RD-16kQ, IQ=O.587mA a) 120kQ b) 170kQ C) 183kQ d) 188kQ 28) Determine the differential mode gain of the MOSFET differential amplifier with the parameters X=O.01 VI , Kn=l mA/V2, RD-16kQ, IQ=O.587mA a) 8.67 b) 9.67 c) 10.23 d) 6.54 29) Determine the common mode gain of the MOSFET differential amplifier with the parameters X=O.01 VI , Kn=l mA/V2, RD-16kQ, IQ=O.587mA a) -0.0356 b) -.05452 c) -0.0469 d) -0.0345

30) A MOSFET based differential amplifier with active load has a differential mode gain of

2k

31) Find the maximum allowed output negative swing without the transistor entering saturation, and a) 1.27 ml/ b) 1.47 mV c) 1.67 mV d) 1.87 rnV 32) The corresponding maximum input signal permitted is

a) b) c) d)

1.64 mV 1.74 rnV 1.84 mV 1.94 mV 33) The maximum possible positive output signal swing as determined by the need to keep the transistor in the active region. a) 9.7 + lc b) 9.7 - lc

c) d)

1 0.3 +

10.3 - lc 34) The transistor in the circuit below is biased at a dc collector current of 0.5 mA. What is the voltage gain?

b) -10 V/V c) -100 V/V d) -1000 V/V 35) The maximum possible positive output signal swing as determined by the need to keep the transistor in the active region. a) -1.7 V b) -2.7 V c) -3.7 v d) -4.7 V

ANALOG ELECTRONICS CIRCUITS (18ECC210J) UNIT-4 (MCO)

1. Efficiency of Class AB Amplifier A) 25 to 30%

B)70 to 80%

C) Better than Class A but less than Class B D)Higher than 80% 2. Which power amplifier is used for switching design? A) Class A B) Class B C) ClassC D 3. If the output power is 50W and average DC power required from power supply is 200W then the efficiency of Class A amplifier? A) 0.25 B)O.50 C)0.75 D)l.o

the

4. A transformer coupled Class A power amplifier has a load of IOOQ on the secondary. If the turn ...