53 + Interview Questions in Bipolar Junction Triodes (Bjts) in Electronic Devices & Circuits Page 1 InterviewSolution

1.	Which of the following is true for the saturation region of BJT transistor?(a) The collector current is inversely proportional to the base current(b) The collector current is proportional to the square root of the collector current(c) The natural logarithm of the collector current is directly proportional to the base current(d) None of the mentionedThe question was asked by my school principal while I was bunking the class.Asked question is from BJT Circuits at DC in chapter Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» Correct option is (b) The collector CURRENT is proportional to the square root of the collector current The explanation is: The collector current is DIRECTLY proportional to the base current in the SATURATION REGION of the BJT.

Discussion

2.	The SI units of transconductance is(a) Ampere/ volt(b) Volt/ ampere(c) Ohm(d) SiemensThe question was posed to me during an interview for a job.Query is from Small Signal Operations and Model topic in chapter Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» CORRECT ANSWER is (a) AMPERE/ volt Explanation: Transcoductance is GIVEN by Ic/Vt.

Discussion

3.	Suppose the hop rate is increased to 2 hops/bit and the receiver uses square law combining the signal over two hops. The hopping bandwidth for this channel is(a) 3.2767 MHz(b) 13.1068 MHz(c) 26.2136 MHz(d) 1.6384 MHzThe question was asked in my homework.The query is from Spread Spectrum topic in division Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The correct choice is (b) 13.1068 MHZ For explanation I would say: If the hopping rate is 2 hops/BIT and the bit rate is 100 bits/sec, then, the hop rate is 200 hops/sec. The minimum frequency separation for orthogonality 2/T400 Hz. Since there are N32767 STATES of the shift register and for each state we SELECT one of two frequencies separated by 400 Hz, the hopping bandwidth is 13.1068 MHz.

Discussion

4.	In a fast FH spread spectrum system, the information is transmitted via FSK with non coherent detection. Suppose there are N = 3 hops/bit with hard decision decoding of the signal in each hop. The channel is AWGN with power spectral density 0.5No and an SNR 20 ~13 dB (total SNR over the three hops). The probability of error for this system is(a) 0.013(b) 0.0013(c) 0.049(d) 0.0049This question was posed to me during an online interview.The above asked question is from Spread Spectrum in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The correct option is (b) 0.0013 Best EXPLANATION: The total SNR for three HOPS is 20 ~ 13 dB. Therefore the SNR per HOP is 20/3. The probability of a chip error with non-coherent detection is

Discussion

5.	The maximum possible negative output signal swing as determined by the need to keep the transistor in the active region.(a) 0.5 V(b) 1 V(c) 5 V(d) 10 VI got this question in my homework.The doubt is from BJT in Amplifier Design topic in division Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» Correct choice is (C) 5 V To EXPLAIN: It is given by -10 + 10 + (IC X Rc). Putting Ic as 5 mA we get 5V.

Discussion

6.	Find Ai.(a) 182 A/A(b) 364 A/A(c) 546 A/A(d) 728 A/AThis question was posed to me in an international level competition.Asked question is from Basic BJT Amplifier Configuration in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» Correct option is (d) 728 A/A To explain: (Vo X R in) / (Vi X RL) GIVES the REQUIRED VALUE of Ai.

Discussion

7.	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 VI had been asked this question during a job interview.The question is from BJT in Amplifier Design in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» RIGHT option is (d) -4.7 V To explain: The MAXIMUM voltage SWING is given by -10 + 0.3 + (Ic X RC). Putting Ic as 5 mA, we GET -4.7 mV.

Discussion

8.	Find Gvo.(a) 53.3 V/V(b) 63.3 V/V(c) 73.3 V/V(d) 83.3 V/VI have been asked this question at a job interview.My query is from Basic BJT Amplifier Configuration in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» Correct CHOICE is (d) 83.3 V/V Easiest explanation: Gvo = (Avo X input resistance) / (input resistance + SIGNAL resistance).

Discussion

9.	Find Av.(a) 9.09 V/V(b) 10 V/V(c) 90.9 V/V(d) 100 V/VI had been asked this question in examination.Query is from Basic BJT Amplifier Configuration in chapter Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» CORRECT CHOICE is (C) 90.9 V/V For EXPLANATION: Av = AVO X Rl/Ro+Rl or 100 X 1000/1000+100 or 90.9 V/V.

Discussion

10.	Find R (in 1) for R (sig) = 5 kΩ.(a) 2.4 kΩ(b) 4.8 kΩ(c) 17.3 kΩ(d) 34.6 kΩThis question was posed to me at a job interview.This question is from Biasing in BJT Amplifier Circuits in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The correct option is (a) 2.4 kΩ Easiest EXPLANATION: It is the PARALLEL COMBINATION of the 32 kΩ resistor and 2.6 kΩ resistor respectively.

Discussion

11.	Find R (in 2).(a) 2.4 kΩ(b) 4.8 kΩ(c) 17.3 kΩ(d) 34.6 kΩThe question was asked in exam.My doubt is from Biasing in BJT Amplifier Circuits topic in division Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The correct answer is (a) 2.4 kΩ For explanation I WOULD say: It is the PARALLEL COMBINATION of the 32 kΩ RESISTOR and 2.6 kΩ resistor respectively.

Discussion

12.	Find R out.(a) 146 Ω(b) 292 Ω(c) 584 Ω(d) 1168 ΩThe question was asked in an online quiz.This key question is from Basic BJT Amplifier Configuration topic in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» RIGHT answer is (a) 146 Ω Explanation: Rout = Rl (1 – Gvo/Gv). Put in the RESPECTIVE VALUES and solve.

Discussion

13.	The value of the voltage gain is _______________(a) -2 V/V(b) -4 V/V(c) -10 V/V(d) -20 V/VThe question was posed to me at a job interview.I'd like to ask this question from BJT in Amplifier Design topic in division Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» Right choice is (a) -2 V/V The best EXPLANATION: The voltage is 400 X IC where Ic is 5 mA.

Discussion

14.	The processing gain is(a) 14 dB(b) 37 dB(c) 58 dB(d) 104 dBI had been asked this question in semester exam.I need to ask this question from Spread Spectrum topic in chapter Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» RIGHT answer is (B) 37 dB Explanation: PG= (10^7)/(2 x 1000) = 5000 or 37 db.

Discussion

15.	Find R(C) to establish a dc collector voltage of about +5V.(a) 5 kΩ(b) 10 kΩ(c) 15 kΩ(d) 20 kΩI got this question in class test.My question is from Basic BJT Amplifier Configuration in division Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The correct CHOICE is (d) 20 kΩ Easy EXPLANATION: VC = 15 – RC.Ic 5 = 15 – Rc * 0.99 * 0.5m Rc = 20.2kΩ = 20kΩ.

Discussion

16.	Find Gv.(a) 53.4 V/V(b) 72.7 V/V(c) 83.3 V/V(d) 90.9 V/VI had been asked this question in an interview for job.This interesting question is from Basic BJT Amplifier Configuration in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The CORRECT choice is (b) 72.7 V/V The explanation: Gv = (Gvo X AV) / AVO or 83.3 X 90.9 / 100 V/V.

Discussion

17.	The coding gain is(a) 7 dB(b) 12 dB(c) 14 dB(d) 24 dBThe question was posed to me in exam.I want to ask this question from Spread Spectrum in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» CORRECT CHOICE is (a) 7 dB Explanation: 0.5 x 10 = 5 or 7 db is the coding GAIN.

Discussion

18.	The chip duration is(a) 1µs(b) 0.1 µs(c) 0.1 ms(d) 1 msI got this question during an interview for a job.My question is from Spread Spectrum topic in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» Correct answer is (b) 0.1 µs Easy EXPLANATION: TC = 1/(10^7) or 0.1 µs.

Discussion

19.	The period of PN sequence is(a) 1.5 µs(b) 15 µs(c) 6.67 ns(d) 0.67 nsI had been asked this question during a job interview.This question is from Spread Spectrum topic in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» Correct OPTION is (B) 15 µs For EXPLANATION I WOULD say: The period of the PN sequence is T = NTc = 15 x 0.1 = 1.5 s

Discussion

20.	Which of the following is true?(a) Ib = ß Ic(b) Ib = ß + 1/ Ic(c) Ib = Ic/ß(d) Ib = Ic/ ß – 1I had been asked this question in quiz.Origin of the question is Small Signal Operations and Model in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The CORRECT ANSWER is (c) IB = Ic/ß The explanation: The correct RELATIONSHIP between Ic and Ie is Ib = Ic/ß.

Discussion

21.	Which of the following represents the correct mathematical form of the term denoted by the symbol Rp?(a) ß/gm(b) Vt/Ib(c) All of the mentioned(d) None of the mentionedI have been asked this question in unit test.This intriguing question originated from Small Signal Operations and Model in chapter Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» CORRECT CHOICE is (C) All of the mentioned The explanation: Both of the EXPRESSIONS are IDENTICAL.

Discussion

22.	The PN sequence length is(a) 10(b) 12(c) 15(d) 18This question was addressed to me in a national level competition.My question comes from Spread Spectrum topic in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» Correct answer is (C) 15 Explanation: The PN SEQUENCE length is N = 2^m – 1 = 16 – 1 = 15.

Discussion

23.	For a BJt Vt is 5 V, Rc = 1000 ohm and bias current Ic is 12 mA. The value of the voltage gain is __________(a) -1.2 V/V(b) -2.4 V/V(c) -3.6V/V(d) -4.8 V/VThis question was posed to me during an online exam.I want to ask this question from BJT in Amplifier Design topic in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The CORRECT choice is (b) -2.4 V/V The EXPLANATION is: Voltage GAIN is (Ic X Rc ) / VT.

Discussion

24.	Which of the following is true for a pnp transistor in active region?(a) CB junction is reversed bias and the EB junction is forward bias(b) CB junction is forward bias and the EB junction is forward bias(c) CB junction is forward bias and the EB junction is reverse bias(d) CB junction is reversed bias and the EB junction is reverse biasThe question was asked in class test.This key question is from BJT Circuits at DC topic in chapter Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The CORRECT OPTION is (a) CB junction is reversed bias and the EB junction is forward bias To elaborate: Whether the TRANSISTOR in npn or PNP, for it be in active region the EB junction must be reversed bias the CB junction must be forward bias.

Discussion

25.	Which of the following is true for the active region of an npn transistor?(a) The collector current is directly proportional to the base current(b) The potential difference between the emitter and the collector is less than 0.4 V(c) All of the mentioned(d) None of the mentionedI got this question in a national level competition.My doubt is from BJT Circuits at DC topic in division Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» Correct choice is (c) All of the mentioned For EXPLANATION: The base current and the COLLECTOR current are directly proportional to each other and the potential DIFFERENCE between the collector and the base is always less than 0.4 V.

Discussion

26.	In cut off mode(a) The base-emitter junction is forward biased and emitter-collector junction is reversed biased(b) The base-emitter junction is forward biased and emitter-collector junction is forward biased(c) The base-emitter junction is reversed biased and emitter-collector junction is reversed biased(d) The base-emitter junction is reversed biased and emitter-collector junction is forward biasedThe question was posed to me during an interview for a job.I need to ask this question from BJTs Device Strucutres and Physical Operations topic in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The CORRECT CHOICE is (c) The base-emitter junction is reversed BIASED and emitter-collector junction is reversed biased Explanation: In cut-off mode there is no current flowing through the BJT hence both junctions must be reversed biased else if either of them is forward biased then the current will flow.

Discussion

27.	The potential difference between the base and the collector Vcb in a pnp transistor in saturation region is ________(a) -0.2 V(b) -0.5V(c) 0.2 V(d) 0.5 VThis question was addressed to me by my school principal while I was bunking the class.The origin of the question is BJT Circuits at DC topic in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The correct ANSWER is (b) -0.5V Easiest EXPLANATION: The VALUE of Vcb is -0.5V for a PNP transistor and 0.5V for an NPN transistor.

Discussion

28.	The collector current Ic is related to the emitter current Ie by a factor k. If b is the transistor parameter then the value of k in terms of b is(a) k = b/(b + 1)(b) k = (b + 1)/b(c) b = (k + 1)/k(d) None of the mentionedI have been asked this question by my school teacher while I was bunking the class.Enquiry is from BJTs Device Strucutres and Physical Operations topic in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The correct answer is (a) K = b/(b + 1) To elaborate: Ic = k IE(GIVEN) and ALSO Ie = (b + 1)/b Ic(standard RESULT).Equating these two results we get k = b/(b + 1).

Discussion

29.	The correct relation between the emitter current Ie and the base current Ib is given by(a) Ib = (1 + α) Ie(b) Ib = (α – 1) Ie(c) Ie = (1 – ß) Ib(d) Ie = (1 + ß) IbI had been asked this question by my college director while I was bunking the class.This is a very interesting question from BJTs Current-Voltage Characteristics in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» Correct CHOICE is (d) Ie = (1 + ß) Ib Easy EXPLANATION: The correct MATHEMATICAL EXPRESSION are Ie = (1 – ß) Ib and Ib = (1 – α) Ie respectively.

Discussion

30.	The corresponding maximum input signal permitted is(a) 1.64 mV(b) 1.74 mV(c) 1.84 mV(d) 1.94 mVThis question was posed to me in an international level competition.My question is from BJT in Amplifier Design topic in chapter Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» Correct choice is (d) 1.94 MV Easy EXPLANATION: If we assume linear OPERATION right to saturation we can use the gain Av to calculate the MAXIMUM input signal. Thus for an output swing ∆ Vo = 0.8 we have ∆ Vi = ∆ Vo / Av = -0.7 / -360 = 1.94 mV.

Discussion

31.	The range for the transistor parameter also referred as common-emitter current gain has a value of__________ for common devices.(a) 50-200(b) 400-600(c) 750-1000(d) > 1000This question was posed to me during a job interview.Asked question is from BJTs Device Strucutres and Physical Operations in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» RIGHT option is (a) 50-200 The EXPLANATION: Most commonly USED transistors have a voltage gain of in the RANGE of 50-200. Only some SPECIALLY designed transistors have a transistor parameter in the range of 1000.

Discussion

32.	Which of the following is true for a pnp transistor in saturationregion?(a) CB junction is reversed bias and the EB junction is forward bias(b) CB junction is forward bias and the EB junction is forward bias(c) CB junction is forward bias and the EB junction is reverse bias(d) CB junction is reversed bias and the EB junction is reverse biasI have been asked this question in examination.My doubt is from BJT Circuits at DC in chapter Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» Correct OPTION is (b) CB JUNCTION is forward BIAS and the EB junction is forward bias The best explanation: WHETHER the transistor in npn or pnp, for it be in saturation region the EB junction must be forward bias the CB junction must be forward bias.

Discussion

33.	The correct expression relating the emitter current Ie to the collector current Ic is(a) Ie = α Ic(b) Ic = α Ic(c) Ie = ß Ic(d) Ic = ß IcThis question was addressed to me in an interview for internship.I want to ask this question from BJTs Current-Voltage Characteristics topic in chapter Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» Right ANSWER is (B) IC = α Ic The best explanation: IE = Ic/α or Ic = α Ie

Discussion

34.	If a BJT is to be used as a switch, it must operate in____________(a) Cut-off mode or active mode(b) Active Mode or saturation mode(c) Cut-off mode or saturation mode(d) Cut-off mode or saturation mode or active modeI got this question in an interview for job.Question is taken from BJTs Device Strucutres and Physical Operations topic in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The correct choice is (c) Cut-off MODE or saturation mode The EXPLANATION is: A BJT OPERATES as an AMPLIFIERS in active mode and as a switch in cut-off or saturation mode.

Discussion

35.	For a pnp transistor in the active region the value of Vce (potential difference between the collector and the base) is(a) Less than 0.3V(b) Less than 3V(c) Greater than 0.3V(d) Greater than 3VThis question was posed to me in class test.I'm obligated to ask this question of BJT Circuits at DC in division Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The correct CHOICE is (a) Less than 0.3V Best explanation: For a pnp transistor VCE is less than 0.3V, for an npn transistor it is GREATER than 0.3V.

Discussion

36.	Which of the following is true for a typical active region of an npn transistor?(a) The potential difference between the emitter and the collector is less than 0.5 V(b) The potential difference between the emitter and the collector is less than 0.4 V(c) The potential difference between the emitter and the collector is less than 0.3 V(d) The potential difference between the emitter and the collector is less than 0.2 VThis question was addressed to me during an interview.My question is taken from BJT Circuits at DC topic in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» Right option is (c) The POTENTIAL DIFFERENCE between the emitter and the COLLECTOR is less than 0.3 V The explanation: Most commonly used transistors have VCE less than 0.4 V for the active region.

Discussion

37.	Which of the following condition is true for cut-off mode?(a) The collector current Is zero(b) The collector current is proportional to the base current(c) The base current is non zero(d) All of the mentionedThis question was posed to me during an interview.My doubt is from BJT Circuits at DC topic in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» CORRECT option is (a) The COLLECTOR CURRENT Is zero The best explanation: The BASE current as well as the collector current are zero in cut-off mode.

Discussion

38.	For the BJT to operate in active mode Collector-Base junction must be(a) Heavily doped(b) Must reversed bias(c) Must be forward bias(d) Lightly dopedI have been asked this question during a job interview.My question is taken from BJTs Current-Voltage Characteristics in chapter Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» CORRECT option is (b) Must reversed bias The EXPLANATION: The BJT operates in active mode when the collector-Base JUNCTION is reversed bias. Also doping cannot PREVENT saturation of the transistor.

Discussion

39.	The value of the thermal voltage at room temperature can be approximated as(a) 25 mV(b) 30 mV(c) 35 mV(d) 40 mVThis question was posed to me in an interview.This is a very interesting question from BJTs Current-Voltage Characteristics topic in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» Correct ANSWER is (a) 25 mV Explanation: THERMAL voltage is given by kT/q which at T = 25 degrees CELSIUS is APPROXIMATELY 25 mV.

Discussion

40.	The magnitude of the thermal voltage is given by(a) k/Tq(b) kT/q(c) q/Kt(d) Tk/qThis question was addressed to me in semester exam.This is a very interesting question from BJTs Current-Voltage Characteristics in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» CORRECT option is (b) kT/q Explanation: kT/q is the correct mathematical EXPRESSION for the thermal VOLTAGE.

Discussion

41.	Which of the following is true for a npn transistor in the saturation region?(a) The potential difference between the collector and the base is approximately 0.2V(b) The potential difference between the collector and the base is approximately 0.3V(c) The potential difference between the collector and the base is approximately 0.4V(d) The potential difference between the collector and the base is approximately 0.5VThe question was asked in an interview for internship.My question is from BJT Circuits at DC in chapter Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The correct choice is (d) The POTENTIAL difference between the COLLECTOR and the base is approximately 0.5V Easy explanation: The COMMONLY USED npn TRANSISTORS have a potential difference of around 0.5V between he collector and the base.

Discussion

42.	Which of the following is true for the cut-off region in an npn transistor?(a) Potential difference between the emitter and the base is smaller than 0.5V(b) Potential difference between the emitter and the base is smaller than 0.4V(c) The collector current increases with the increase in the base current(d) The collector current is always zero and the base current is always non zeroThis question was addressed to me by my college professor while I was bunking the class.I'd like to ask this question from BJT Circuits at DC topic in chapter Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» RIGHT option is (b) POTENTIAL difference between the emitter and the BASE is smaller than 0.4V To explain I WOULD say: Both collector and emitter current are zero in cut-off REGION.

Discussion

43.	If a BJT is to be used as an amplifier, then it must operate in___________(a) Cut-off mode(b) Active mode(c) Saturation mode(d) All of the mentionedThe question was asked in an online interview.I'm obligated to ask this question of BJTs Device Strucutres and Physical Operations in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» RIGHT choice is (b) ACTIVE MODE Explanation: A BJT operates as an amplifiers in active mode and as a SWITCH in cut-off or saturation mode.

Discussion

44.	Which of the following is not a part of a BJT?(a) Base(b) Collector(c) Emitter(d) None of the mentionedThe question was posed to me by my college director while I was bunking the class.My query is from BJTs Device Strucutres and Physical Operations topic in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The CORRECT ANSWER is (d) None of the mentioned For explanation: BJT CONSISTS of three semiconductor regions, base region, EMITTER region and collector region.

Discussion

45.	The number of pn junctions in a BJT is/are(a) 1(b) 2(c) 3(d) 4I had been asked this question in an international level competition.My question is based upon BJTs Device Strucutres and Physical Operations in division Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The correct choice is (B) 2 The best explanation: There are TWO pn JUNCTIONS, base-emitter JUNCTION and collector-emitter junction respectively.

Discussion

46.	On which of the following does the collector current not depends upon?(a) Saturation current(b) Thermal voltage(c) Voltage difference between the base and emitter(d) None of the mentionedI got this question in my homework.My question is taken from BJTs Device Strucutres and Physical Operations in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The correct option is (d) None of the mentioned Explanation: COLLECTOR current depends LINEARLY of the SATURATION current and EXPONENTIALLY to the ratio of the VOLTAGE difference between the base and collector and thermal voltage.

Discussion

47.	Collector current (Ic) reaches zero when(a) Vce = Vt ln (Isc/I)(b) Vt = Vce ln (Isc/I)(c) Vce = Vt ln (I/Isc)(d) Vce = Vt ln (Isc + I/I)The question was asked during a job interview.I need to ask this question from BJTs Current-Voltage Characteristics in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» CORRECT answer is (a) Vce = VT ln (ISC/I) EASIEST explanation: Ic = Is exp (Vbe/Vt) – Isc exp(Vbc/Vt). In this expression put ic = 0 and simplify.

Discussion

48.	The Early Effect is also called as(a) Base-width modulation effect(b) Base-width amplification effect(c) Both of the mentioned(d) None of the mentionedThe question was posed to me during an interview for a job.This intriguing question originated from BJTs Current-Voltage Characteristics in division Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» The correct option is (a) Base-WIDTH modulation effect Easiest explanation: At a given value of vBE, increasing vCE increases the reverse-bias voltage on the collector–base junction, and thus increases the width of the depletion region of this junction. This in turn results in a DECREASE in the effective base width W. Also the SATURATION current is inversely proportional to the width, the saturation current will INCREASE and also makes collector current increases PROPORTIONALLY. This is the Early Effect. For the reasons mentioned above, it is also known as the base-width modulation effect.

Discussion

49.	The curve between the collector current versus the potential difference between the base and emitter is(a) A straight line inclined to the axes(b) A straight line parallel to the x-axis(c) An exponentially varying curve(d) A parabolic curveI have been asked this question in an interview.My enquiry is from BJTs Current-Voltage Characteristics topic in chapter Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» CORRECT ANSWER is (C) An exponentially varying curve Explanation: The natural logarithm of the collector current depends directly on the the potential DIFFERENCE between the base and the emitter.

Discussion

50.	In which of the following modes can a BJT be used?(a) Cut-off mode(b) Active mode(c) Saturation mode(d) All of the mentionedI have been asked this question in exam.Query is from BJTs Device Strucutres and Physical Operations topic in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits
Answer» RIGHT choice is (d) All of the mentioned Explanation: These THREE are the DEFINED REGIONS in which a BJT OPERATES.

Discussion

Explore topic-wise InterviewSolutions in .

The SI units of transconductance is(a) Ampere/ volt(b) Volt/ ampere(c) Ohm(d) SiemensThe question was posed to me during an interview for a job.Query is from Small Signal Operations and Model topic in chapter Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits

Find Ai.(a) 182 A/A(b) 364 A/A(c) 546 A/A(d) 728 A/AThis question was posed to me in an international level competition.Asked question is from Basic BJT Amplifier Configuration in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits

Find Gvo.(a) 53.3 V/V(b) 63.3 V/V(c) 73.3 V/V(d) 83.3 V/VI have been asked this question at a job interview.My query is from Basic BJT Amplifier Configuration in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits

Find Av.(a) 9.09 V/V(b) 10 V/V(c) 90.9 V/V(d) 100 V/VI had been asked this question in examination.Query is from Basic BJT Amplifier Configuration in chapter Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits

Find R (in 1) for R (sig) = 5 kΩ.(a) 2.4 kΩ(b) 4.8 kΩ(c) 17.3 kΩ(d) 34.6 kΩThis question was posed to me at a job interview.This question is from Biasing in BJT Amplifier Circuits in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits

Find R (in 2).(a) 2.4 kΩ(b) 4.8 kΩ(c) 17.3 kΩ(d) 34.6 kΩThe question was asked in exam.My doubt is from Biasing in BJT Amplifier Circuits topic in division Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits

Find R out.(a) 146 Ω(b) 292 Ω(c) 584 Ω(d) 1168 ΩThe question was asked in an online quiz.This key question is from Basic BJT Amplifier Configuration topic in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits

The value of the voltage gain is _______________(a) -2 V/V(b) -4 V/V(c) -10 V/V(d) -20 V/VThe question was posed to me at a job interview.I'd like to ask this question from BJT in Amplifier Design topic in division Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits

The processing gain is(a) 14 dB(b) 37 dB(c) 58 dB(d) 104 dBI had been asked this question in semester exam.I need to ask this question from Spread Spectrum topic in chapter Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits

Find R(C) to establish a dc collector voltage of about +5V.(a) 5 kΩ(b) 10 kΩ(c) 15 kΩ(d) 20 kΩI got this question in class test.My question is from Basic BJT Amplifier Configuration in division Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits

Find Gv.(a) 53.4 V/V(b) 72.7 V/V(c) 83.3 V/V(d) 90.9 V/VI had been asked this question in an interview for job.This interesting question is from Basic BJT Amplifier Configuration in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits

The coding gain is(a) 7 dB(b) 12 dB(c) 14 dB(d) 24 dBThe question was posed to me in exam.I want to ask this question from Spread Spectrum in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits

The chip duration is(a) 1µs(b) 0.1 µs(c) 0.1 ms(d) 1 msI got this question during an interview for a job.My question is from Spread Spectrum topic in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits

The period of PN sequence is(a) 1.5 µs(b) 15 µs(c) 6.67 ns(d) 0.67 nsI had been asked this question during a job interview.This question is from Spread Spectrum topic in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits

Which of the following is true?(a) Ib = ß Ic(b) Ib = ß + 1/ Ic(c) Ib = Ic/ß(d) Ib = Ic/ ß – 1I had been asked this question in quiz.Origin of the question is Small Signal Operations and Model in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits

The PN sequence length is(a) 10(b) 12(c) 15(d) 18This question was addressed to me in a national level competition.My question comes from Spread Spectrum topic in portion Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits

The corresponding maximum input signal permitted is(a) 1.64 mV(b) 1.74 mV(c) 1.84 mV(d) 1.94 mVThis question was posed to me in an international level competition.My question is from BJT in Amplifier Design topic in chapter Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits

The magnitude of the thermal voltage is given by(a) k/Tq(b) kT/q(c) q/Kt(d) Tk/qThis question was addressed to me in semester exam.This is a very interesting question from BJTs Current-Voltage Characteristics in section Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits

The number of pn junctions in a BJT is/are(a) 1(b) 2(c) 3(d) 4I had been asked this question in an international level competition.My question is based upon BJTs Device Strucutres and Physical Operations in division Bipolar Junction Triodes (BJTs) of Electronic Devices & Circuits