96 + Interview Questions in Transistor Biasing And Thermal Stabilization in Electronic Devices & Circuits Page 2 InterviewSolution

51.	Q point can be set to work on active region requires particular conditions. What are they?(a) BE reverse biased and BC forward biased(b) BE reverse biased and BC reverse biased(c) BE forward biased and BC reverse biased(d) BE forward biased and BC forward biasedThe question was posed to me during an interview for a job.Asked question is from The Operating Point in section Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» CORRECT answer is (c) BE forward biased and BC reverse biased To explain: BJT REQUIRES the forward voltage nearly equal to 0.7v and the p-junction should be more positive in BE junction and n region should be more positive in BC junction. This will MAKE the CURRENT to flow through emitter which is the sum of current through base and emitter.

Discussion

52.	The total thermal resistance of a power transistor and heat sink is 20°C/W. The ambient temperature is 25°C and (TJ)MAX=200°C. If VCE=4V, find the maximum collector current that the transistor can carry without destruction. What will be the allowed value of collector current if ambient temperature rises to 75°C?(a) 3.67A(b) 7.56A(c) 2.19A(d) 1.56AThe question was asked in semester exam.The above asked question is from Thermal Stability topic in division Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer»

Discussion

53.	In an ideal stable self – bias circuit, what should be the current IB with respect to IC?(a) IB should be 20% of IC(b) IB should be 5% of IC(c) IB should be 10% of IC(d) IB should be 50% of ICThe question was asked in an interview.The question is from Stabilization against Variations in VBE and Beta for Self Bias Circuit topic in section Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The correct ANSWER is (c) IB should be 10% of IC The best explanation: Ideally, the resistor values are designed in a way that the voltage DROPS across RE is approximately 10% of Vcc and IB should be 10% of Ic. Hence, stable SELF – BIAS circuits work best at low power supply voltages.

Discussion

54.	How many main types of bias circuits are there in bipolar transistors?(a) 3(b) 4(c) 5(d) 6The question was posed to me in homework.This intriguing question originated from Stabilization against Variations in VBE and Beta for Self Bias Circuit topic in chapter Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The correct OPTION is (c) 5 To elaborate: There are five main type of biasing CIRCUITS. They are Fixed Bias, Collector – to – BASE Bias, VOLTAGE Divider Bias, Fixed Bias with Emitter Resistor and Emitter Bias.

Discussion

55.	The collector current (IC) that is obtained in a self biased transistor is_________(a) (VTH – VBE)/RE(b) (VTH + VBE)/RE(c) (VTH – VBE)/RE(d) (VTH + VBE)/REThis question was addressed to me by my college director while I was bunking the class.This intriguing question originated from Self-Bias topic in portion Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» CORRECT option is (a) (VTH – VBE)/RE The BEST I can explain: The collector current is ANALYSED by the DC analysis of a transistor. It involves the DC equivalent CIRCUIT of a transistor. The base current is FIRST found and the collector current is obtained from the relation, IC=IBβ.

Discussion

56.	The negative feedback does good for DC signal by_________(a) decreasing the gain(b) increasing the gain(c) stabilising the operating point(d) increasing the stability factorThis question was posed to me in semester exam.I would like to ask this question from Collector-to-Base Bias in chapter Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The CORRECT option is (c) stabilising the operating point Explanation: The RESISTOR RB can provide negative feedback for both AC and DC signals. The negative feedback for DC signal is done GOOD as it can provide stable operating point. On the other SIDE, the negative feedback is badly done for AC signal by decreasing the voltage GAIN.

Discussion

57.	Which of the following has a negative temperature coefficient of resistance?(a) Thtermistor(b) capacitor(c) sensistor(d) diodeI got this question by my school principal while I was bunking the class.I need to ask this question from Thermistor and Sensistor Compensation in portion Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» Right ANSWER is (a) Thtermistor Easy explanation: The THERMISTOR decreases EXPONENTIALLY with RESPECT to T. The Thermistor RT is used to minimize the INCREASE in collector current.Thus it has a negative temperature coefficient.

Discussion

58.	What happens if collector current increases in a collector emitter feedback circuit?(a) Emitter voltage increases therefore base voltage increases(b) Emitter voltage decreases therefore base voltage decreases(c) Emitter voltage increases therefore base voltage decreases(d) Emitter voltage decreases therefore base voltage increasesI have been asked this question in an international level competition.Question is taken from Collector-Emitter Feedback Bias in portion Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» RIGHT answer is (a) Emitter voltage increases therefore base voltage increases To explain I WOULD say: If the collector current VC is increased, the corresponding emitter current also increases. Which in turn CAUSES the voltage across RE to increase. This in turn causes a proportional rise in the base voltage since VB = VE + VBE.

Discussion

59.	In a silicon transistor, which of the following change significantly to the change in IC?(a) VCE(b) IB(c) VBE(d) IEI got this question in examination.This intriguing question comes from Bias Compensation in portion Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer»

Discussion

60.	A silicon NPN transistor is used and it has a large value of β. Find the required value of R2 when IC=1mA.(a) 10kΩ(b) 20kΩ(c) 30kΩ(d) 40kΩThe question was posed to me in an internship interview.I'd like to ask this question from Self-Bias in portion Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» Correct CHOICE is (d) 40kΩ To EXPLAIN: For silicon, VBE=0.8V, VCE=0.2V. IC=VTH-VBE/RE. By PITTING the values, we have VTH=1.3V. R2 can be FOUND from, VCCR2/R1+R2. We get R2=40KΩ.

Discussion

61.	What is the function of RE in the collector emitter feedback circuit?(a) To improve stability and decrease positive feedback(b) To improve stability and increase positive feedback(c) To improve stability and decrease negative feedback(d) To improve stability and increase negative feedbackI have been asked this question in class test.This is a very interesting question from Collector-Emitter Feedback Bias in section Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The correct answer is (d) To improve stability and increase negative feedback For EXPLANATION I would say: In a collector feedback circuit, the emitter resistor provides additional stability along with increasing the negative feedback sent to the collector. The ADDITION of the emitter RESISTANCE enables the TRANSISTOR’s emitter to no longer be grounded to zero – volt POTENTIAL.

Discussion

62.	The demerit of a collector to base bias is_________(a) its need of high resistance values(b) its dependence on β(c) its independence on β(d) the positive feedback produced by the base resistorThis question was posed to me in semester exam.My question comes from Collector-to-Base Bias topic in chapter Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The CORRECT OPTION is (a) its NEED of high RESISTANCE values Explanation: When the stability factor S=1, the collector resistor value should be very large when compared to the base resistor. So, when RC is large we need to provide large power supply which increases the cost. At the same time, as the base resistor is small we need to provide small power supply.

Discussion

63.	There are two transistors A and B having ‘S’ as 25 and 250 respectively, on comparing the value of S, we can say B is more stable than A.(a) True(b) FalseThis question was addressed to me during an online exam.I'd like to ask this question from Bias Stability topic in section Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» Correct CHOICE is (b) False Explanation: More the value of S, lesser the STABILITY, SINCE A has lesser S value the CHANGE in beta does not affect much on the collector current. When S is HIGH, even if IB changes by a small value, the IC current will drastically vary. Hence stability factor must possess lesser value for the proper working of a transistor.

Discussion

64.	The Q-point of a transistor is made to shift between Active and cut off Region, then how does the transistor behave?(a) Switch(b) Amplifier(c) Inverter(d) BulbThis question was addressed to me in a national level competition.The query is from The Operating Point in section Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» Right option is (a) Switch Easiest explanation: When the Q point lies in cut off, No current flows and HENCE it acts as a closed switch. When the Q point is shifted to saturation, Current flows through the CIRCUIT creating a closed switch. Thus the current flow MAKES the TURN on and off of switch.

Discussion

65.	Which of the following has a negative temperature coefficient of resistance?(a) capacitor(b) diode(c) thermistor(d) sensistorThis question was posed to me in an interview for job.My query is from Bias Compensation topic in division Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The correct answer is (d) SENSISTOR Explanation: The sensistor has a positive temperature coefficient of RESISTANCE. It is a temperature SENSITIVE RESISTOR. It is a heavily doped semiconductor. When voltage is decreased, the net forward EMITTER voltage decreases. As a result the collector current decreases.

Discussion

66.	When the temperature is increased, what happens to the collector current after a feedback is given?(a) it remains same(b) it increases(c) it cannot be predicted(d) it decreasesThe question was asked in an online interview.Enquiry is from Self-Bias topic in portion Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» Correct option is (d) it decreases Best explanation: Before the feedback is applied, when the temperature is INCREASED, the REVERSE saturation increases. The collector CURRENT also increases. When the feedback is applied, the drop across the emitter RESISTOR increases with decreasing collector current and the thermal RUNWAY too.

Discussion

67.	Compensation techniques refer to the use of_________(a) diodes(b) capacitors(c) resistors(d) transformersThis question was posed to me by my school teacher while I was bunking the class.This interesting question is from Bias Compensation topic in section Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» Correct answer is (a) diodes Easy explanation: Compensation techniques refer to the use of temperature sensitive DEVICES such as thermistors, diodes, transistors, SENSISTORS etc to compensate variation in CURRENTS. Sometimes for excellent bias and THERMAL stabilization, both stabilization and compensation techniques are used.

Discussion

68.	Where should be the bias point set in order to make transistor work as an amplifier?(a) Cut off(b) Active(c) Saturation(d) Cut off and SaturationI had been asked this question by my college director while I was bunking the class.I'm obligated to ask this question of The Operating Point in section Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» Correct ANSWER is (b) Active For EXPLANATION: To OPERATE transistor as an amplifier, it REQUIRES more current amplification factor and in cut off and saturation, the current amplification is less, therefore active region is better to fix the Q point.

Discussion

69.	The feedback helps to maintain a constant gain value.(a) True(b) FalseI got this question in unit test.Query is from Emitter Feedback Bias in portion Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The CORRECT answer is (a) True The EXPLANATION: From the equation IE = IC + IB, once the IE increases, the base current will reduce because of emitter feedback, resulting in a constant gain. In emitter feedback circuits, the resistance RE is USED to provide negative feedback which is given to the base to maintain a constant gain.

Discussion

70.	Collector base feedback and emitter feedback combined together provide stability for self – bias circuits.(a) True(b) FalseThe question was asked in homework.I'm obligated to ask this question of Stabilization against Variations in VBE and Beta for Self Bias Circuit topic in chapter Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The correct option is (a) True The best explanation: Collector BASE FEEDBACK and emitter feedback COMBINED PROVIDE stability for self – bias circuits. This is because the emitter base junction is forward biased due to the voltage drop ACROSS RE.

Discussion

71.	The thermal runway is avoided in a self bias because_________(a) of its independence of β(b) of the positive feedback produced by the emitter resistor(c) of the negative feedback produced by the emitter resistor(d) of its dependence of βThe question was asked by my college director while I was bunking the class.Query is from Self-Bias in section Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The correct answer is (c) of the NEGATIVE FEEDBACK produced by the EMITTER resistor The explanation is: The SELF destruction of a transistor due to increase temperature is called thermal run AWAY. It is avoided by the negative feedback produced by the emitter resistor in a self bias. The IC which is responsible for the damage is reduced by decreased output signal.

Discussion

72.	For a given transistor, the thermal resistance is 8°C/W and for the ambient temperature TA is 27°C. If the transistor dissipates 3W of power, calculate the junction temperature (TJ).(a) 51°C(b) 27°C(c) 67°C(d) 77°CI had been asked this question during an interview for a job.My question is based upon Thermal Stability in division Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» CORRECT ANSWER is (a) 51°C Easy EXPLANATION: We KNOW, TJ-TA=HPD TJ=TA+HPD=27+8*3=51°C.

Discussion

73.	The compensation techniques are used to_________(a) increase stability(b) increase the voltage gain(c) improve negative feedback(d) decrease voltage gainThe question was posed to me in unit test.This is a very interesting question from Bias Compensation in division Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» CORRECT option is (B) increase the VOLTAGE gain Explanation: Usually, the negative feedback is used to produce a stable operating point. But it reduces the voltage gain of the circuit. This sometimes is intolerable and should be avoided in some APPLICATIONS. So, the biasing techniques are used.

Discussion

74.	What values of VBE and β would provide maximum stability?(a) VBE = 5V, β = 50(b) VBE = 4V, β = 100(c) VBE = 4.5V, β = 50(d) It is irrelevantThis question was posed to me in homework.This interesting question is from Stabilization against Variations in VBE and Beta for Self Bias Circuit topic in division Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» Correct answer is (d) It is irrelevant The best I can explain: In a stable BIAS CIRCUIT, the VARIATIONS in the value of VBE and β do not affect the stability of the SYSTEM. The current through the emitter remains unchanged.

Discussion

75.	In the circuit, the transistor has a large β value (VBE=0.7V). Find the current through RC.(a) 0.5mA(b) 2mA(c) 1mA(d) 1.6mAI got this question during a job interview.I need to ask this question from Self-Bias in division Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» RIGHT CHOICE is (C) 1mA To explain I would SAY: We KNOW, IC=VTH-VBE/RE =9*3/9=3V. IC=3-0.7/2.3=1mA.

Discussion

76.	For an emitter feedback bias circuit, the value of VCC = 10V, RB = 10Kohm, RE=1Kohm and RC=2Kohm, if current flowing through collector is 0.5mA, what is the voltage difference between collector and emitter?(a) 8.5V(b) 9V(c) 10V(d) 10.5VThe question was asked in unit test.The query is from Emitter Feedback Bias topic in division Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The CORRECT OPTION is (a) 8.5V For explanation I WOULD say: VCC = Vce + IC RC + IE RE Vce = VCC – IC RC – IE RE Vce = 10-0.5-1 Vce = 8.5V.

Discussion

77.	How does the negative feedback help a collector emitter feedback circuit?(a) Helps make it more predictable(b) Provides opposing change in base voltage(c) Helps make it more predictable, provides opposing change in base voltage(d) It doesn’t affectI have been asked this question in quiz.Question is from Collector-Emitter Feedback Bias in section Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» Right CHOICE is (c) Helps make it more predictable, provides opposing CHANGE in base voltage Explanation: The NEGATIVE feedback in a COLLECTOR emitter feedback circuit provides a negative feedback which in turn helps make the circuit more predictable as it provides opposing change in the base voltage which cancels out any change in the collector current.

Discussion

78.	For an ideal transistor having a fixed bias configuration, what will be the value of Beta?(a) 0(b) 2(c) -1(d) 1The question was asked in exam.The question is from Bias Stability in chapter Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The CORRECT OPTION is (c) -1 Easiest explanation: S = 1 + Beta S = 0 Beta = -1.

Discussion

79.	For a fixed bias circuit having Ic = 0.3mA and In=0.0003mA, S is______________(a) 100(b) 0(c) 11(d) 111The question was asked during an interview.My enquiry is from Bias Stability in portion Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» CORRECT ANSWER is (C) 11 Explanation: For FIXED BIAS S=1+beta Beta=IC/IB=10 S=1+10=11.

Discussion

80.	For a n-p-n transistor, the collector current changed from 0.2mA to 0.22mA resulting a change of base emitter voltage from 0.8v to 0.8005V. What is the value of Stability factor?(a) 0(b) 0.25(c) 0.04(d) 0.333This question was addressed to me in unit test.My question is based upon Bias Stability in division Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The CORRECT option is (C) 0.04 For explanation: Change in VBE = 0.0005V Change in COLLECTOR current = 0.02mA S = 0.02m/0.0005 = 0.04.

Discussion

81.	For the voltage divider circuit, if a diode is connected in reverse direction across the base Find the value of β? (Vd=1.2v and input is 1V)(a) 0(b) 50(c) 100(d) cannot be determinedThis question was addressed to me in semester exam.Question is from The Operating Point topic in division Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» Right answer is (d) cannot be determined Explanation: SINCE the INPUT voltage is less than the DIODE voltage, transistor never turns on during the positive HALF cycle, hence it is difficult to measure the β value. Also during a negative half cycle, the diode will be turned off and hence no current FLOWS, so the value if beta cannot be determined, it can be 0 because the manufacturer will certainly provide the value.

Discussion

82.	Thermistors provide precise temperature measurements.(a) True(b) FalseThe question was posed to me in an online interview.This question is from Thermistor and Sensistor Compensation topic in chapter Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» Right option is (a) True The explanation is: THERMISTORS can be USED for precise temperature MEASUREMENTS. It CONTROLS the temperature and the compensation due to a large variation in RESISTANCE with temperature.

Discussion

83.	Thermal stability is dependent on thermal runaway which is_________(a) an uncontrolled positive feedback(b) a controlled positive feedback(c) an uncontrolled negative feedback(d) a controlled negative feedbackThis question was posed to me during an online interview.Question is taken from Thermal Stability in division Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» Right choice is (a) an uncontrolled positive feedback Explanation: Thermal runaway is a SELF DESTRUCTION process in which an increase in temperature CREATES such a condition which in turn increases the temperature again. This uncontrolled rise in temperature causes the COMPONENT to get DAMAGED.

Discussion

84.	Which process plays a crucial role in devising the independency of operating point over the variations in temperature or transistor parameters?(a) Bias stabilization(b) Bias compensation(c) Bias stabilization & compensation(d) NO processI had been asked this question during an interview.Question is from Thermistor and Sensistor Compensation topic in portion Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» CORRECT choice is (a) Bias stabilization Easy explanation: Bias stabilization is a process which makes the operating (Q) point INDEPENDENT of change in temperature or any change in transistor parameters. As Q-point EXHIBITS its independent nature over the numerous VARIATIONS, it plays a significant role in providing the stability to greater level especially for self-bias, fixed-bias and collector to base bias circuits. Since the stability factor of circuit gets affected due to several variations, bias stabilization has a provision of maintaining the Q-point condition irrespective of the CHANGES in temperature or transistor parameters and thereby ensuring the confined level of bias stability to circuits.

Discussion

85.	For a fixed bias circuit having RC=4.7KΩ and RB=1KΩ, VCC=10V, and base current at Bias point was found to be 0.2µA, Find β?(a) 100(b) 106(c) 125(d) 0This question was addressed to me in a job interview.This intriguing question originated from The Operating Point topic in division Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The CORRECT ANSWER is (B) 106 The EXPLANATION: ICQ = Vcc/Rc = 2.12mA β=ICQ/IBQ=106.

Discussion

86.	When the temperature is increased, what happens to the collector current after a feedback is given?(a) it remains same(b) it increases(c) it cannot be predicted(d) it decreasesThe question was posed to me in an interview for internship.Enquiry is from Collector-to-Base Bias in division Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The correct answer is (d) it decreases To explain: Before the feedback is applied, when the temperature is INCREASED, the REVERSE saturation INCREASES. The COLLECTOR current ALSO increases. When the feedback is applied, the base current increases with decreasing collector current and the thermal runway too.

Discussion

87.	Thermal stability can be obtained by_________(a) shifting operating point(b) increasing power supply(c) heat sink(d) decreasing current at collectorThe question was posed to me in class test.The query is from Thermal Stability in division Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» Correct ANSWER is (c) heat sink Explanation: As power transistors handle LARGE currents, they always heat up during operation. Generally, power transistors are mounted in large METAL CASE to provide a large area from which the heat generated by the DEVICE radiates.

Discussion

88.	When the collector current is increased in a transistor_________(a) the reverse current is increased(b) the temperature is increased(c) collisions of electrons decrease(d) the emitter does not emit electronsThis question was posed to me in my homework.This interesting question is from Thermal Runaway topic in chapter Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» Right answer is (b) the TEMPERATURE is increased For explanation: As the collector current is increased, the emitter releases more number of ELECTRONS. This CAUSES more collisions of electrons at collector. This happens in a CYCLE and produces such a condition in which temperature is further more increased.

Discussion

89.	On which factor/s do/does the values of thermal resistance depend?(a) Size of transistor(b) Type of cooling system(c) Transistor size & cooling system type(d) Number of holesI got this question in an online interview.My query is from Thermistor and Sensistor Compensation topic in division Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The correct option is (c) Transistor size & cooling system type For explanation: The value of thermal resistance usually depends on the size of transistor, type of heat transfer mechanism and the type of cooling systems (natural cooling, FORCED air cooling, etc). It also depends on the thermal connectivity of device to a heat sink or metal chassis. Thermal resistance of a power transistor is always LESS than that of logic level transistor. The value of thermal resistance should be essentially SMALL so as to allow the smooth flow of heat from the JUNCTION of the power transistor to the SURROUNDING.

Discussion

90.	A Thermistor has low resistance.(a) True(b) FalseThis question was addressed to me in an interview.I want to ask this question from Thermistor and Sensistor Compensation topic in section Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» RIGHT ANSWER is (b) False Easiest EXPLANATION: Thermistors generally have an extremely high value of resistance. Cables with a SHIELD are required for usage to minimize the INTERFERENCE.

Discussion

91.	Why do we require RE for a good stable bias circuit?(a) To obtain a current IE sensitive to β and VBE(b) To obtain a current IB sensitive to β and VBE(c) To obtain a current IE insensitive to β and VBE(d) To obtain a current IB insensitive to β and VBEThis question was addressed to me in quiz.The query is from Stabilization against Variations in VBE and Beta for Self Bias Circuit in chapter Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The correct ANSWER is (c) To obtain a current IE INSENSITIVE to β and VBE The explanation is: The aim of having a bias CIRCUIT is to maintain a stable current or voltage, regardless of other PARAMETERS changing. Hence, we need RE to get a stable IE current, without RE the VALUE of IE changes drastically with a small change in β.

Discussion

92.	What are the disadvantages of collector emitter feedback bias circuits?(a) Requires few resistors(b) Provides a lot of stability(c) Provides negative feedback(d) Provides positive feedbackThis question was addressed to me in an online interview.My doubt stems from Collector-Emitter Feedback Bias in chapter Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The correct option is (c) PROVIDES negative feedback Best EXPLANATION: A COLLECTOR emitter bias circuit provides negative feedback as well as requires multiples resistors for a small change. The negative feedback limits the frequency range it will work in. Higher frequencies will provide poor performance. It also requires a greater NUMBER of resistors just to provide a STABILITY against a small parameter.

Discussion

93.	In order to make an amplifier which of the following biasing technique is used more?(a) Fixed bias(b) Self bias(c) Collector to base bias(d) Emitter feedback biasThis question was addressed to me in examination.This interesting question is from Emitter Feedback Bias topic in chapter Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» Right option is (d) Emitter feedback bias The EXPLANATION is: Since emitter feedback bias CIRCUIT, the OUTPUT swing is very much stable and the DESIGN shows more stability to changes in temperature. Voltage DIVIDER circuit is the most used among all of the biasing technique because of its gain stability and impedance parameters.

Discussion

94.	When the β value is large for a given transistor, the IC and VCE values are given by_________(a) (VCC-VBE)/RB, VCC-RCIC(b) (VCC+VBE)/RB, VCC-RC(IC+IB)(c) (VCC+VBE)/RB, VCC+RC(IC+IB)(d) (VCC+VBE)/RB, VCC+RC(IC-IB)I have been asked this question by my college professor while I was bunking the class.This interesting question is from Collector-to-Base Bias topic in division Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The correct CHOICE is (a) (VCC-VBE)/RB, VCC-RCIC The explanation is: The base current IB is zero when β value is LARGE. So, the VCE changes to VCC-RCIC. The collector current IC is changed to (VCC-VBE)/RB from β(VCC-VBE)/(1+ β)RE+ RB.

Discussion

95.	Among the following statements which one is true according to feedback bias?(a) Fixed bias is more stable than emitter feedback bias(b) Fixed bias produces more feedback than emitter feedback bias(c) Emitter feedback bias is more stable than the fixed bias(d) Fixed and emitter bias have same stability and feedbackI got this question during an internship interview.The doubt is from Emitter Feedback Bias topic in section Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» The correct choice is (C) Emitter feedback bias is more STABLE than the FIXED bias Best explanation: Since S is having a linear relationship with beta in fixed bias, it is less stable, but in emitter feedback bias, S is not exactly linear with a beta. In fixed bias, even a small change in ICo changes the IC value very much, but due to negative feedback in emitter bias, ICodoes not change the IC value maintaining its STABILITY.

Discussion

96.	The temperature changes do not affect the Stability.(a) True(b) FalseThis question was posed to me during an online exam.Question is from Bias Stability in section Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits
Answer» RIGHT option is (b) False Explanation: The TEMPERATURE CHANGES the value of BETA which in turn changes the stability of the transition. The temperature changes affect the mobility of the charge carries which results in a change of the current parameters affecting stability.

Discussion

Explore topic-wise InterviewSolutions in .

In a silicon transistor, which of the following change significantly to the change in IC?(a) VCE(b) IB(c) VBE(d) IEI got this question in examination.This intriguing question comes from Bias Compensation in portion Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits

The feedback helps to maintain a constant gain value.(a) True(b) FalseI got this question in unit test.Query is from Emitter Feedback Bias in portion Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits

In the circuit, the transistor has a large β value (VBE=0.7V). Find the current through RC.(a) 0.5mA(b) 2mA(c) 1mA(d) 1.6mAI got this question during a job interview.I need to ask this question from Self-Bias in division Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits

For an ideal transistor having a fixed bias configuration, what will be the value of Beta?(a) 0(b) 2(c) -1(d) 1The question was asked in exam.The question is from Bias Stability in chapter Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits

For a fixed bias circuit having Ic = 0.3mA and In=0.0003mA, S is______________(a) 100(b) 0(c) 11(d) 111The question was asked during an interview.My enquiry is from Bias Stability in portion Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits

Thermistors provide precise temperature measurements.(a) True(b) FalseThe question was posed to me in an online interview.This question is from Thermistor and Sensistor Compensation topic in chapter Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits

A Thermistor has low resistance.(a) True(b) FalseThis question was addressed to me in an interview.I want to ask this question from Thermistor and Sensistor Compensation topic in section Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits

The temperature changes do not affect the Stability.(a) True(b) FalseThis question was posed to me during an online exam.Question is from Bias Stability in section Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits