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ece > m2 - chap 5 > Flashcards

m2 - chap 5 Flashcards

1
Q


Which of the following techniques can be used in the sinusoidal ac analysis of transistor networks?

A) Small-signal
B) Large-signal
C) Small- or large-signal
D) None of the above

A

C) Small- or large-signal

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2
Q

What is the limit of the efficiency defined by = Po/Pi?

A) Greater than 1
B) Less than 1
C) Always 1
D) None of the above

A

B) Less than 1

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3
Q

Which of the following define(s) the conversion efficiency?

A) Ac power to the load/ac input power
B) Ac power to the load/dc power supplied
C) Dc output power/ac input power
D) All of the above

A

B) Ac power to the load/dc power supplied

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4
Q

Which of the following should be done to obtain the ac equivalent of a network?

A) Set all dc sources to zero
B) Replace all capacitors by a short-circuit equivalent.
C) Remove all elements bypassed by the short-circuit equivalent.
D) All of the above

A

D) All of the above

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5
Q

The ______ model suffers from being limited to a particular set of operating conditions if it is to be considered accurate.

A) hybrid equivalent
B) re
C) B
D) Thevenin

A

A) hybrid equivalent

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6
Q

The _______ model fails to account for the output impedance level of the device and the feedback effect from output to input.

A) hybrid equivalent
B) re
C) B
D) Thevenin

A

B) re

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7
Q

Which of the following is (are) true regarding the input impedance for frequencies in the midrange < 100 kHz of a BJT transistor amplifier?

A) The input impedance is purely resistive.
B) It varies from a few ohms to mega ohms.
C) An ohmmeter cannot be used to measure the small-signal ac input impedance.
D) All of the above

A

D) All of the above

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8
Q

Which of the following is (are) true regarding the output impedance for frequencies in the midrange < 100 kHz of a BJT transistor amplifier?

A) The output impedance is purely resistive.
B) It varies from a few ohms to more than 2 MS.
C) An ohmmeter cannot be used to measure the small-signal ac output impedance.
D) All of the above

A

D) All of the above

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9
Q

What is the range of the current gain for BJT transistor amplifiers?

A) less than 1
B) 1 to 100
C) above 100
D) All of the above

A

D) All of the above

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10
Q

The input impedance of a BJT amplifier is purely _____ in nature and can vary from a few _________ to _______.

A) resistive, ohms, megohms
B) capacitive, microfarads, farads
C) inductive, millihenrys, henrys
D) None of the above

A

A) resistive, ohms, megohms

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11
Q

For BJT amplifiers, the ________ gain typically ranges from a level just less than 1 to a level that may exceed 1000.

A) voltage
B) current
C) impedance
D) All of the above

A

B) current

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12
Q

What is the unit of the parameter ho?

A) Volt
B) Ohm
C) Siemen
D) No unit

A

C) Siemen

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13
Q

Which of the h-parameters corresponds to re in a common-base configuration?

A) hib
B) hfb
C) hrb
D) hob

A

A) hib

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14
Q

What is the range of the input impedance of a common-base configuration?

A) A few ohms to a maximum of 50 Ω
Β) 1 ΚΩ to 5 ΚΩ
C) 100 ΚΩ to 500 ΚΩ
D) 1 MΩ to 2 MΩ

A

A) A few ohms to a maximum of 50 Ω

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15
Q

What is the typical value of the current gain of a common-base configuration?

A) Less than 1
B) Between 1 and 50
C) Between 100 and 200
D) Undefined

A

A) Less than 1

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16
Q

What is the controlling current in a common-base configuration?

A) le
B) Ic
C) lb
D) None of the above

A

A) le

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17
Q

What is the typical range of the output impedance of a common-emitter configuration?

Α) 10 Ω to 100 Ω
Β) 1 ΚΩ to 5 ΚΩ
C) 40 kΩ to 50 kΩ
D) 500 ΚΩ to 1 ΜΩ

A

C) 40 kΩ to 50 kΩ

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18
Q

Under which of the following conditions is the output impedance of the network approximately equal to RC for a common-emitter fixed-bias configuration?

A) ro ≥ 10Rc
B) ro < 10Rc
C) re < ro
D) re > To

A

A) ro≥ 10Rc

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19
Q

Under which of the following condition(s) is the current gain Av ≈ B?

A) ro > 10RC
B) RB > 10re
C) ro > 10RC and RB > 10re
D) None of the above

A

C) ro > 10RC and RB > 10re

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20
Q

What does the negative sign in the voltage gain of the common-emitter fixed-bias configuration indicate?

A) The output and input voltages are 180° out of phase.
B) Gain is smaller than 1.
C) Gain is larger than 1.
D) None of the above

A

A) The output and input voltages are 180° out of phase.

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21
Q

For the common-emitter fixed-bias configuration, there is a phase shift between the input and output signals.

A) 0
B) 45°
C) 90°
D) 180°

A

D) 180°

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22
Q

Which of the following configurations has an output impedance Zo equal to RC?

A) Fixed-bias common-emitter
B) Common-emitter voltage-divider with bypass capacitor
C) Common-emitter voltage-divider without bypass capacitor
D) All of the above

A

D) All of the above

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23
Q

Which of the following configurations has the lowest output impedance?

A) Fixed-bias
B) Voltage-divider
C) Emitter-follower
D) None of the above

A

C) Emitter-follower

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23
Q

Which of the following configurations has a voltage gain of -RC/re?

A) Fixed-bias common-emitter
B) Common-emitter voltage-divider with bypass capacitor
C) Fixed-bias common-emitter and voltage-divider with bypass capacitor
D) Common-emitter voltage-divider without bypass capacitor

A

C) Fixed-bias common-emitter and voltage-divider with bypass capacitor

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24
Q

The ________ configuration is frequently used for impedance matching.

A) fixed-bias
B) voltage-divider bias
C) emitter-follower
D) collector feedback

A

C) emitter-follower

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24
Q

For the collector dc feedback configuration, there is a _____ phase shift between the input and output signals.

A) 0°
B) 45°
C) 90°
D) 180°

A

D) 180°

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25
Q

Which of the following represent(s) the advantage(s) of the system approach over the r-model approach?

A) Thevenin’s theorem can be used.
B) The effect of changing the load can be determined by a simple equation.
C) There is no need to go back to the ac equivalent model and analyze the entire network.
D) All of the above

A

D) All of the above

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25
Q

The emitter-follower configuration has a ____ impedance at the input and a ___ impedance at the output.

A) low, low
B) low, high
C) high, low
D) high, high

A

C) high, low

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26
Q

Which of the following gains is less than 1 for a common-base configuration?

A) Ai
B) Av
C) Ap
D) None of the above

A

A) Ai

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26
Q

Which of the following conditions must be met to allow the use of the approximate approach in a voltage-divider bias configuration?

A) Bre > 10R2
B) BRE > 10R2
C) BRE < 10R2
D) Bre <10R2

A

A) Bre > 10R2

26
Q

The loaded voltage gain of an amplifier is always more than the no-load level.

A) True
B) False

A

B) False

27
Q

Which of the following is (are) true to achieve a good overall voltage gain for the circuit?

A) The effect of Rs and RL must be considered as a product.
B) The effect of Rs and RL must be considered as a product and evaluated individually.
C) The effect of Rs and RL must be evaluated individually.
D) None of the above

A

B) The effect of Rs and RL must be considered as a product and evaluated individually.

27
Q

Which one of the following configurations has the lowest input impedance?

A) Fixed-bias
B) Common-base
C) Emitter-follower
D) Voltage-divider

A

B) Common-base

27
Q

The smaller the level of RL, the larger the level of ac voltage gain.

A) True
B) False

A

B) False

27
Q

In an unbypassed emitter bias configuration hie replaces _______ in the re model.

A) re
B) B
C) Bre
D) Ib

A

C) Bre

27
Q

The current gain for the Darlington connection is

A) B1 * (B2/2)
B) B1 * B2
C) B1/B2
D) B1 * (B2-1)

A

B) B1 * B2

28
Q

What is the voltage gain of a feedback pair connection?

A) 1
B) -1
C) 100
D) -100

A

A) 1

28
Q

The _______ the source resistance and/or ________ the load resistance, the less the overall gain of an amplifier.

A) smaller, smaller
B) smaller, larger
C) larger, smaller
D) larger, larger

A

C) larger, smaller

28
Q

The _______ of the input signal is one of the first concerns in the sinusoidal ac analysis of transistor networks.

A) period
B) frequency
C) magnitude
D) None of the above

A

C) magnitude

28
Q

______ can be applied to determine the response of the ac equivalent circuit.

A) Mesh analysis
B) Node analysis
C) Thevenin’s theorem
D) All of the above

A

D) All of the above

29
Q

Which of the following is referred to as the reverse transfer voltage ratio?

A) hi
B) hr
C) hf
D) ho

A

B) hr

30
Q

The input and output signals are __________ for the typical transistor amplifier at frequencies that permit ignoring the effects of the reactive elements.

A) in phase
B) 180° out of phase
C) either in phase or 180° out of phase
D) None of the above

A

C) either in phase or 180° out of phase

30
Q

For transistor amplifiers, the no-load voltage gain is ______ the loaded voltage gain.

A) smaller than
B) greater than
C) the same as
D) None of the above

A

B) greater than

31
Q

The peak value of the ac input signal is controlled by the _________ in a transistor network for the frequencies in the low to midrange.

A) resistors
B) applied dc voltage
C) capacitors
D) None of the above

A

B) applied dc voltage

31
Q

The ________ model(s) is (are) commonly used in the small-signal ac analysis of transistor networks.

A) re
B) hybrid equivalent
C) re and hybrid equivalent
D) None of the above

A

C) re and hybrid equivalent

31
Q

For a common-base configuration, the input impedance is relatively _______ and the output impedance quite _______

A) high, small
B) small, high
C) small, small
D) high, high

A

B) small, high

32
Q

In a common-emitter configuration _____ is the controlling current while _________ is the controlled current.

A) IC, IB
B) IC, IE
C) IB, IC
D) None of the above

A

C) IB, IC

32
Q

One junction of an operating transistor is __________ and the other one is _________

A) forward-biased, forward-biased
B) forward-biased, reverse-biased
C) reverse-biased, reverse-biased
D) None of the above

A

B) forward-biased, reverse-biased

33
Q

The level of re is determined by

A) a
B) IE
C) B
D) IB

A

B) IE

33
Q

The output voltage and the input voltage are __________ for the common-base configuration.

A) 45° out of phase
B) 90° out of phase
C) 180’ out of phase
D) in phase

A

D) in phase

34
Q

The output voltage and the input voltage are __________ for the common-emitter configuration.

A) in phase
B) 45° out of phase
C) go out of phase
D) 180° out of phase

A

D) 180° out of phase

35
Q

The common-emitter configuration has a __________ level of input impedance with a _________ voltage and current gain.

A) moderate, high
B) low, moderate
C) Low, Low
D) high, low

A

A) moderate, high

36
Q

________ refers to the forward transfer current ratio.

A) hi
B) hr
C) hf
D) ho

A

C) hf

37
Q

For the common-emitter and common-base configurations, the magnitude of ______ and _______ is often not included in the model.

A) hr, ho
B) hi, he
C) hi, hr
D) he, ho

A

A) hr, ho

38
Q

In a fixed-bias network, the input signal Vi is applied to the ________ of the transistor while the output Vo is off the ___________.

A) base, collector
B) base, emitter
C) emitter, collector
D) None of the above

A

A) base, collector

38
Q

In a voltage-divider bias configuration, the voltage-divider equation is used to determine the

A) ac level of Vb
B) dc level of IB
C) dc level of VB
D) ac level of Ib

A

C) dc level of VB

39
Q

The bypass capacitor in a common-emitter configuration _________ the voltage gain.

A) significantly decreases
B) significantly increases
C) slightly increases
D) slightly decreases

A

B) significantly increases

39
Q

In a voltage-divider bias configuration, there can be a measurable difference in the results for if the condition ro≥ 10RC is not satisfied.

A) Zo
B) Av
C) Ai
D) All of the above

A

C) Ai

40
Q

In an emitter-follower, the voltage gain is ________

A) slightly less than 1
B) slightly more than 1
C) a very large value
D) None of the above

A

A) slightly less than 1

41
Q

In an emitter-follower, the output voltage is _________ with the input voltage.

A) 45° out of phase
B) 90° out of phase
C) 180° out of phase
D) in phase

A

D) in phase

42
Q

An emitter-follower has _____ impedance at the input an _________ impedance at the output.

A) high, high
B) low, high
C) high, low
D) low, low

A

C) high, low

43
Q

_______ is slightly affected if the condition ro > 10RE is not satisfied in the analysis of an emitter- follower configuration.

A) Zi
B) Zo
C) Av
D) Ai

A

C) Av

44
Q

A common-base configuration has ______ impedance at the input and ______ impedance at the output.

A) high, high
B) high, low
C) low, low
D) low, high

A

D) low, high

45
Q

In a common-base configuration, the input and output voltages are __________ and the output and input currents are __________

A) 180° out of phase, 180° out of phase
B) 180° out of phase, in phase
C) in phase,180° out of phase
D) in phase, in phase

A

D) in phase, in phase

46
Q

Ideally, the changes in the load resistor or the source resistor should have _____________ effect on all the parameters of the two-port model.

A) a great
B) a moderate
C) no
D) None of the above

A

C) no

47
Q

The loaded voltage gain of an amplifier is __________ the no-load level.

A) always more than
B) always less than
C) always the same as
D) None of the above

A

B) always less than

48
Q

The coupling capacitor places the load and collector resistors in a ________ arrangement.

A) series
B) parallel
C) series-parallel
D) None of the above

A

B) parallel

49
Q

The dc load line and ac load line both have the same _______.

A) x-intercept
B) y-intercept
C) slope
D) Q-point

A

D) Q-point

50
Q

The _______ the level of RL, the ______ the level of ac voltage gain.

A) smaller, higher
B) larger, lower
C) smaller, lower
D) None of the above

A

C) smaller, lower

51
Q

The _______ the source resistance, the _______ the overall gain of an amplifier.

A) larger, higher
B) larger, lower
C) Lower, lower
D) None of the above

A

B) larger, lower

52
Q

The ac voltage gain of a Darlington connection is about

A) o
B) 1
C) BD
D) None of the above

A

B) 1

53
Q

The feedback pair uses a(n) ______ transistor driving a(n) ________ transistor, the two device acting effectively much like one pnp transistor.

A) pnp, npn
B) pnp, pnp
C) npn, npn
D) None of the above

A

A) pnp, npn

54
Q

In an unbypassed emitter-bias configuration _____ replaces re in the hybrid equivalent circuit.

A) hie
B) hfe
C) hre
D) hoe

A

A) hie

55
Q

In a hybrid equivalent circuit, _______ is determined to make it easier to find the other parameters.

A) Zi
B) Zo
C) Ai
D) Av

A

D) Av

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