m2 - chap 5 Flashcards
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
C) Small- or large-signal
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
B) Less than 1
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
B) Ac power to the load/dc power supplied
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
D) All of the above
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) hybrid equivalent
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
B) re
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
D) All of the above
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
D) All of the above
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
D) All of the above
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) resistive, ohms, megohms
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
B) current
What is the unit of the parameter ho?
A) Volt
B) Ohm
C) Siemen
D) No unit
C) Siemen
Which of the h-parameters corresponds to re in a common-base configuration?
A) hib
B) hfb
C) hrb
D) hob
A) hib
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 few ohms to a maximum of 50 Ω
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) Less than 1
What is the controlling current in a common-base configuration?
A) le
B) Ic
C) lb
D) None of the above
A) le
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
C) 40 kΩ to 50 kΩ
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) ro≥ 10Rc
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
C) ro > 10RC and RB > 10re
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) The output and input voltages are 180° out of phase.
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°
D) 180°
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
D) All of the above
Which of the following configurations has the lowest output impedance?
A) Fixed-bias
B) Voltage-divider
C) Emitter-follower
D) None of the above
C) Emitter-follower
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
C) Fixed-bias common-emitter and voltage-divider with bypass capacitor
The ________ configuration is frequently used for impedance matching.
A) fixed-bias
B) voltage-divider bias
C) emitter-follower
D) collector feedback
C) emitter-follower
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°
D) 180°
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
D) All of the above
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
C) high, low
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) Ai
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) Bre > 10R2
The loaded voltage gain of an amplifier is always more than the no-load level.
A) True
B) False
B) False
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
B) The effect of Rs and RL must be considered as a product and evaluated individually.
Which one of the following configurations has the lowest input impedance?
A) Fixed-bias
B) Common-base
C) Emitter-follower
D) Voltage-divider
B) Common-base
The smaller the level of RL, the larger the level of ac voltage gain.
A) True
B) False
B) False
In an unbypassed emitter bias configuration hie replaces _______ in the re model.
A) re
B) B
C) Bre
D) Ib
C) Bre
The current gain for the Darlington connection is
A) B1 * (B2/2)
B) B1 * B2
C) B1/B2
D) B1 * (B2-1)
B) B1 * B2
What is the voltage gain of a feedback pair connection?
A) 1
B) -1
C) 100
D) -100
A) 1
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
C) larger, smaller
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
C) magnitude
______ 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
D) All of the above
Which of the following is referred to as the reverse transfer voltage ratio?
A) hi
B) hr
C) hf
D) ho
B) hr
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
C) either in phase or 180° out of phase
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
B) greater than
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
B) applied dc voltage
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
C) re and hybrid equivalent
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
B) small, high
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
C) IB, IC
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
B) forward-biased, reverse-biased
The level of re is determined by
A) a
B) IE
C) B
D) IB
B) IE
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
D) in phase
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
D) 180° out of phase
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) moderate, high
________ refers to the forward transfer current ratio.
A) hi
B) hr
C) hf
D) ho
C) hf
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) hr, ho
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) base, collector
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
C) dc level of VB
The bypass capacitor in a common-emitter configuration _________ the voltage gain.
A) significantly decreases
B) significantly increases
C) slightly increases
D) slightly decreases
B) significantly increases
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
C) Ai
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) slightly less than 1
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
D) in phase
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
C) high, low
_______ 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
C) Av
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
D) low, high
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
D) in phase, in phase
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
C) no
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
B) always less than
The coupling capacitor places the load and collector resistors in a ________ arrangement.
A) series
B) parallel
C) series-parallel
D) None of the above
B) parallel
The dc load line and ac load line both have the same _______.
A) x-intercept
B) y-intercept
C) slope
D) Q-point
D) Q-point
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
C) smaller, lower
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
B) larger, lower
The ac voltage gain of a Darlington connection is about
A) o
B) 1
C) BD
D) None of the above
B) 1
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) pnp, npn
In an unbypassed emitter-bias configuration _____ replaces re in the hybrid equivalent circuit.
A) hie
B) hfe
C) hre
D) hoe
A) hie
In a hybrid equivalent circuit, _______ is determined to make it easier to find the other parameters.
A) Zi
B) Zo
C) Ai
D) Av
D) Av
