m2 - chap 5

Question 1


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

Answer 1

C) Small- or large-signal

Question 2

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

Answer 2

B) Less than 1

Question 3

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

Answer 3

B) Ac power to the load/dc power supplied

Question 4

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

Answer 4

D) All of the above

Question 5

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

Answer 5

A) hybrid equivalent

Question 6

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

Answer 6

B) re

Question 7

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

Answer 7

D) All of the above

Question 8

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

Answer 8

D) All of the above

Question 9

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

Answer 9

D) All of the above

Question 10

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

Answer 10

A) resistive, ohms, megohms

Question 11

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

Answer 11

B) current

Question 12

What is the unit of the parameter ho?

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

Answer 12

C) Siemen

Question 13

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

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

Answer 13

A) hib

Question 14

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

Answer 14

A) A few ohms to a maximum of 50 Ω

Question 15

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

Answer 15

A) Less than 1

Question 16

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

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

Answer 16

A) le

Question 17

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

Answer 17

C) 40 kΩ to 50 kΩ

Question 18

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

Answer 18

A) ro≥ 10Rc

Question 19

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

Answer 19

C) ro > 10RC and RB > 10re

Question 20

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

Answer 20

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

Question 21

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°

Answer 21

D) 180°

Question 22

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

Answer 22

D) All of the above

Question 23

Which of the following configurations has the lowest output impedance?

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

Answer 23

C) Emitter-follower

Question 23

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

Answer 23

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

Question 24

The ________ configuration is frequently used for impedance matching. A) fixed-bias B) voltage-divider bias C) emitter-follower D) collector feedback

Answer 24

C) emitter-follower

Question 24

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°

Answer 24

D) 180°

Question 25

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

Answer 25

D) All of the above

Question 25

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

Answer 25

C) high, low

Question 26

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

Answer 26

A) Ai

Question 26

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

Answer 26

A) Bre > 10R2

Question 26

The loaded voltage gain of an amplifier is always more than the no-load level. A) True B) False

Answer 26

B) False

Question 27

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

Answer 27

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

Question 27

Which one of the following configurations has the lowest input impedance? A) Fixed-bias B) Common-base C) Emitter-follower D) Voltage-divider

Answer 27

B) Common-base

Question 27

The smaller the level of RL, the larger the level of ac voltage gain. A) True B) False

Answer 27

B) False

Question 27

In an unbypassed emitter bias configuration hie replaces _______ in the re model. A) re B) B C) Bre D) Ib

Answer 27

C) Bre

Question 27

The current gain for the Darlington connection is A) B1 * (B2/2) B) B1 * B2 C) B1/B2 D) B1 * (B2-1)

Answer 27

B) B1 * B2

Question 28

What is the voltage gain of a feedback pair connection? A) 1 B) -1 C) 100 D) -100

Answer 28

A) 1

Question 28

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

Answer 28

C) larger, smaller

Question 28

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

Answer 28

C) magnitude

Question 28

______ 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

Answer 28

D) All of the above

Question 29

Which of the following is referred to as the reverse transfer voltage ratio? A) hi B) hr C) hf D) ho

Answer 29

B) hr

Question 30

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

Answer 30

C) either in phase or 180° out of phase

Question 30

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

Answer 30

B) greater than

Question 31

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

Answer 31

B) applied dc voltage

Question 31

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

Answer 31

C) re and hybrid equivalent

Question 31

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

Answer 31

B) small, high

Question 32

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

Answer 32

C) IB, IC

Question 32

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

Answer 32

B) forward-biased, reverse-biased

Question 33

The level of re is determined by A) a B) IE C) B D) IB

Answer 33

B) IE

Question 33

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

Answer 33

D) in phase

Question 34

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

Answer 34

D) 180° out of phase

Question 35

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

Answer 35

A) moderate, high

Question 36

________ refers to the forward transfer current ratio. A) hi B) hr C) hf D) ho

Answer 36

C) hf

Question 37

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

Answer 37

A) hr, ho

Question 38

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

Answer 38

A) base, collector

Question 38

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

Answer 38

C) dc level of VB

Question 39

The bypass capacitor in a common-emitter configuration _________ the voltage gain. A) significantly decreases B) significantly increases C) slightly increases D) slightly decreases

Answer 39

B) significantly increases

Question 39

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

Answer 39

C) Ai

Question 40

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

Answer 40

A) slightly less than 1

Question 41

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

Answer 41

D) in phase

Question 42

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

Answer 42

C) high, low

Question 43

_______ 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

Answer 43

C) Av

Question 44

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

Answer 44

D) low, high

Question 45

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

Answer 45

D) in phase, in phase

Question 46

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

Answer 46

C) no

Question 47

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

Answer 47

B) always less than

Question 48

The coupling capacitor places the load and collector resistors in a ________ arrangement. A) series B) parallel C) series-parallel D) None of the above

Answer 48

B) parallel

Question 49

The dc load line and ac load line both have the same _______. A) x-intercept B) y-intercept C) slope D) Q-point

Answer 49

D) Q-point

Question 50

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

Answer 50

C) smaller, lower

Question 51

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

Answer 51

B) larger, lower

Question 52

The ac voltage gain of a Darlington connection is about A) o B) 1 C) BD D) None of the above

Answer 52

B) 1

Question 53

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

Answer 53

A) pnp, npn

Question 54

In an unbypassed emitter-bias configuration _____ replaces re in the hybrid equivalent circuit. A) hie B) hfe C) hre D) hoe

Answer 54

A) hie

Question 55

In a hybrid equivalent circuit, _______ is determined to make it easier to find the other parameters. A) Zi B) Zo C) Ai D) Av

Answer 55

D) Av