Electronic Circuits I Set 6

Electrical Engineering

Practice Mode Previous Next
On This Page

This set of Electronic Circuits 1 Multiple Choice Questions & Answers (MCQs) focuses on Electronic Circuits I Set 6

Q1 | Consider a voltage amplifier having a frequency response of the low-pass STC type with a dc gain of 60 dB and a 3-dB frequency of 1000 Hz. Then the gain db at
  • f = 10 hz is 55 db
  • f = 10 khz is 45 db
  • f = 100 khz is 25 db
  • f = 1mhz is 0 db
Answer: f = 1mhz is 0 db
Explaination:
use standard formulas for frequency response and voltage gain.
Q2 | STC networks can be classified into two categories: low-pass (LP) and high-pass (HP). Then which of the following is true?
  • hp network passes dc and low frequencies and attenuate high frequency and opposite for lp network
  • lp network passes dc and low frequencies and attenuate high frequency and opposite for hp network
  • hp network passes dc and high frequencies and attenuate low frequency and opposite for lp network
  • lp network passes low frequencies only and attenuate high frequency and opposite for hp network
Answer: lp network passes dc and low frequencies and attenuate high frequency and opposite for hp network
Explaination:
by definition a lp network allows dc current (or low frequency current) and an lp network does the opposite, that is, allows high frequency ac current.
Q3 | The signal whose waveform is not effected by a linear circuit is
  • triangular waveform signal
  • rectangular waveform signal
  • sine/cosine wave signal
  • sawtooth waveform signal
Answer: sine/cosine wave signal
Explaination:
only sine/cosine wave are not affected by a linear circuit while all other waveforms are affected by a linear circuit.
Q4 | Which of the following is not a classification of amplifiers on the basis of their frequency response?
  • capacitively coupled amplifier
  • direct coupled amplifier
  • bandpass amplifier
  • none of the mentioned
Answer: none of the mentioned
Explaination:
none of the options provided are correct.
Q5 | General representation of the frequency response curve is called
  • bode plot
  • miller plot
  • thevenin plot
  • bandwidth plot
Answer: bode plot
Explaination:
general representation of frequency response curves are called bode plot. bode plots are also called semi logarithmic plots since they have logarithmic values values on one of the axes.
Q6 | Under what condition can the circuit shown be called a compensated attenuator.
  • c1r1 = c2r2
  • c1r2 = c2r1
  • c1c2 = r1r2
  • r1 = 0
Answer: c1r1 = c2r2
Explaination:
standard condition of a compensated attenuator. here is the derivation for the same.
Q7 | Which of the following is true?
  • coupling capacitors causes the gain to fall off at high frequencies
  • internal capacitor of a device causes the gain to fall off at low frequencies
  • all of the mentioned
  • none of the mentioned
Answer: none of the mentioned
Explaination:
both the statements are false.
Q8 | Which of the following is true?
  • monolithic ic amplifiers are directly coupled or dc amplifiers
  • televisions and radios use tuned amplifiers
  • audio amplifiers have coupling capacitor amplifier
  • all of the mentioned
Answer: all of the mentioned
Explaination:
these all are practical applications of different types of amplifiers.
Q9 | During high frequency applications of a B.J.T., which parasitic capacitors arise between the base and the emitter?
  • cje and cb
  • ccs
  • cb
  • ccs and cb
Answer: cje and cb
Explaination:
there are two capacitors which arise between bases and emitter. one is cje due to depletion region associated between base and emitter. cb is another capacitor which arises due to the accumulation of electrons in the base which further results into the concentration gradient within the base of the transistor.
Q10 | During high frequency applications of a B.J.T., which parasitic capacitors arise between the collector and the emitter?
  • no capacitor arises
  • ccs
  • cb
  • ccs and cb
Answer: no capacitor arises
Explaination:
the emitter and the collector are far away from each other when the b.j.t. is being constructed. hence, we find that they don’t share a common junction where charges can accumulate. thus, no such parasitic capacitors appear.
Q11 | During high frequency applications of a B.J.T, which parasitic capacitors arise between the collector and the base?
  • cje and cb
  • ccs
  • cπ
  • cµ
Answer: cµ
Explaination:
only one capacitor up between the base and the collector. this is due to the depletion region present between the base and the collector region.
Q12 | 3 BJT FREQUENCY RESPONSE
  • cje and cb
  • ccs and cµ
  • cb
  • ccs and cb
Answer: ccs and cµ
Explaination:
there are two capacitors attached to the collector terminal. the collector-base junction provides a depletion capacitance (cµ) while the collector substrate junction provides a certain capacitance (ccs).
Q13 | Which parasitic capacitors do not affect the frequency response of the C.E. stage, of the B.J.T.?
  • cje and cb
  • ccs and cµ
  • cb and cµ
  • no parasitic capacitor gets deactivated
Answer: no parasitic capacitor gets deactivated
Explaination:
while observing the frequency response of a c.e. stage, we find that all the parasitic capacitances of the b.j.t. end up slowing the speed of the b.j.t. the frequency response of this stage is affected by all the parasitic capacitors.
Q14 | Which parasitic capacitors don’t affect the frequency response of the C.B. stage of the B.J.T.?
  • none of the parasitic capacitances
  • all the parasitic capacitances
  • some of the coupling capacitors
  • ccs and cb
Answer: all the parasitic capacitances
Explaination:
all the parasitic capacitors of a
Q15 | Which parasitic capacitors don’t affect the frequency response of the C.C. stage of the B.J.T.?
  • ccs
  • ccs and cb
  • cb
  • ccs and cµ
Answer: ccs
Explaination:
in the follower stage, the load is present at the emitter. the parasitic capacitors present between the collector and the substrate i.e. cµ gets deactivated. this is observed from the small signal analysis where both the terminals of this capacitor get shorted to a.c. ground.
Q16 | If the transconductance of the B.J.T increases, the transit frequency              
  • increases
  • decreases
  • doesn’t get affected
  • doubles
Answer: increases
Explaination:
the transit frequency is directly proportional to the transconductance of the
Q17 | If the total capacitance between the base and the emitter increases by a factor of 2, the transit frequency                      
  • reduces by 2
  • increases by 2
  • reduces by 4
  • increases by 4
Answer: reduces by 2
Explaination:
the transit frequency is almost inversely proportional to the total capacitance between the base and the emitter of the b.j.t. hence, the transit frequency will approximately reduce by 2 and the correct option becomes reduces by 2.
Q18 | Which effect plays a critical role in producing changes in the frequency response of the B.J.T.?
  • thevenin’s effect
  • miller effect
  • tellegen’s effect
  • norton’s effect
Answer: thevenin’s effect
Explaination:
the miller effect results in a change in the capacitance seen between the base and the collector. this is why, it affects the frequency response of the b.j.t. deeply by changing the poles and affecting the high frequency voltage gain stage.
Q19 | If a C.E. stage has a load Rl and transconductance gm, what is the factor by which the capacitance between the base and the collector at the input side gets multiplied?
  • 1 + gmrl
  • 1 – gmrl
  • 1 + 2*gmrl
  • 1 – 2*gmrl
Answer: 1 + gmrl
Explaination:
the low frequency gain of the
Q20 | If a C.E. stage has a load Rl and transconductance gm, what is the factor by which the capacitance between the base and the collector at the output side gets multiplied?
  • 1 + 1/gmrl
  • 1 – 1/gmrl
  • 1 + 2/gmrl
  • 1 – 2/gmrl
Answer: 1 + 1/gmrl
Explaination:
the low frequency response of
Q21 | We cannot use h-parameter model in high frequency analysis because                          
  • they all can be ignored for high frequencies
  • junction capacitances are not included in it
  • junction capacitances have to be included in it
  • ac analysis is difficult for high frequency using it
Answer: junction capacitances are not included in it
Explaination:
the effect of smaller capacitors is considerable in high frequency analysis of analog circuits, and hence they cannot be
Q22 | Given that transition capacitance is 5 pico F and diffusion capacitance is 80 pico F, and base emitter dynamic resistance is 1500 Ω, find the β cut-off frequency.
  • 7.8 x 106 rad/s
  • 8.0 x 106 rad/s c) 49.2 x 106 rad/s d) 22.7 x 106 rad/s
Answer: 7.8 x 106 rad/s
Explaination:
the frequency in radians is calculated by
Q23 | 8 x 106.
  • 200
  • 100
  • 141.42
  • 440.2
Answer: 141.42
Explaination:
the current gain for the ce circuit is a =          β         
Q24 | Gain bandwidth frequency is GBP= 3000 Mhz. The cut-off frequency is f=10Mhz. What is the CE short circuit current gain at the β cutoff frequency?
  • 212
  • 220
  • 300
  • 200
Answer: 212
Explaination:
ft = 3000mhz βfβ = 3000mhz
Q25 | Which of the statement is incorrect?
  • at unity gain frequency the ce short circuit current gain becomes 1
  • unity gain frequency is the same as gain
Answer: at unity gain frequency the ce short circuit current gain becomes 1
Explaination:
gain bandwidth product for any mosfet is ft = gm/2π(cgs+cgd) thus gbp is approximately 5.9 mhz.
Previous Next