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WorksheetsMALVINO BJT
Total questions: 99
Worksheet time: 50mins
For emitter bias, the voltage across the emitter resistor is the same as the voltage between the emitter and the
Base
Collector
Emitter
Ground
For emitter bias, the voltage at the emitter is 0.7 V less than the
Base Voltage
Emitter Voltage
Collector Voltage
Ground Voltage
With voltage-divider bias, the base voltage is
Less than the base supply voltage
Equal to the base supply voltage
Greater than the base supply voltage
Greater than the collector supply voltage
VDB is noted for its
Unstable collector voltage
Varying emitter current
Large base current
Stable Q point
With VDB, an increase in emitter resistance will
Decrease the emitter voltage
Decrease the collector voltage
Increase the emitter voltage
Decrease the emitter current
VDB has a stable Q point like
Base bias
Emitter bias
Collector-feedback bias
Emitter-feedback bias
VDB needs
Only three resistors
Only one supply
Precision resistors
More resistors to work better
VDB normally operates in the
Active region
Cutoff Region
Saturation Region
Breakdown Region
The collector voltage of a VDB circuit is not sensitive to changes in the
Supply Voltage
Emitter Resistance
Current gain
Collector resistance
If the emitter resistance increases in a VDB circuit, the collector voltage
Decreases
Stays the same
Increases
Doubles
Base bias is associated with
Amplifiers
Switching circuits
Stable Q point
Fixed emitter current
If the emitter resistance doubles in a VDB circuit, the collector current will
Double
Drop in half
Remain the same
Increase
If the collector resistance increases in a VDB circuit, the collector voltage will
Decrease
Stays the same
Increase
Double
The Q point of a VDB circuit is
Hypersensitive to changes in current gain
Somewhat sensitive to changes in current gain
Almost totally insensitive to changes in current gain
Greatly affected by temperature changes
The base voltage of two supply emitter bias (TSEB) is
0.7 V
Very large
near 0V
1.3V
If the emitter resistance doubles with TSEB, the collector current will
Drop in half
Stay the same
Double
Increase
If a splash of solder shorts the collector resistor of TSEB, the collector voltage will
Drop to zero
Equal the collector supply voltage
Stay the same
Double
If the emitter resistance increases with TSEB, the collector voltage will
Decrease
Stay the same
Increase
Equal the collector supply voltage
If the emitter resistor opens with TSEB, the collector voltage will
Decrease
Stay the same
Increase slightly
Equal the collector supply voltage
In TSEB, the base current must be very
Small
Large
Unstable
Stable
The Q point of TSEB does not depend on the
Emitter resistance
Collector Resistance
Current gain
Emitter Voltage
The majority carriers in the emitter of a PNP transistor are
Holes
Free electrons
Trivalent atoms
Pentavalent atoms
The current gain of a PNP transistor is
The negative of the NPN current gain
The collector current divided by the emitter current
Near zero
The ratio of collector current to base current
Which is the largest current in a PNP transistor?
Base current
Emitter current
Collector current
None of these
The currents of a PNP transistor are
Usually smaller than NPN currents
Opposite NPN currents
Usually larger than NPN currents
Negative
With PNP voltage-divider bias, you must use
Negative power supplies
Positive power supplies
Resistors
Grounds
For dc, the current in a coupling circuit is
zero
maximum
minimum
average
The current in a coupling circuit for high frequencies is
zero
maximum
minimum
average
A coupling capacitor is
A dc short
A dc short
A dc open and an ac short
A dc short and an ac open
n a bypass circuit, the top of a capacitor is
An open
A short
An ac ground
A mechanical ground
The capacitor that produces an ac ground is called a
Bypass capacitor
Coupling capacitor
Dc open
Ac open
The capacitors of a CE amplifier appear
Open to ac
Shorted to dc
Open to supply voltage
Shorted to ac
Reducing all dc sources to zero is one of the steps in getting the
DC equivalent circuit
AC equivalent circuit
. Complete amplifier circuit
Voltage-divider biased circuit
The ac equivalent circuit is derived from the original circuit by shorting all
Resistors
Capacitors
Inductors
Transistors
When the ac base voltage is too large, the ac emitter current is
Sinusoidal
constant
distorted
alternating
In a CE amplifier with a large input signal, the positive half cycle of the ac emitter current is
. Equal to the negative half cycle
Smaller than the negative half cycle
Larger than the negative half cycle
Equal to the negative half cycle
Ac emitter resistance equals 25 mV divided by the
Quiescent base current
DC emitter current
AC emitter current
Change in collector current
To reduce the distortion in a CE amplifier, reduce the
DC emitter current
Base-emitter voltage
Collector current
AC base voltage
If the ac voltage across the emitter diode is 1 mV and the ac emitter current is 0.1 mA, the ac resistance of the emitter diode is
1 ohm
10 ohm
100 ohm
1 kohm
A graph of ac emitter current versus ac base-emitter voltage applies to the
Transistor
Emitter diode
Collector diode
Power supply
The output voltage of a CE amplifier is
Amplified
Inverted
180 degrees out of phase with the input
All of the above
The emitter of a CE amplifier has no ac voltage because of the
DC voltage on it
Bypass capacitor
Coupling capacitor
Load resistor
The voltage across the load resistor of a CE amplifier is
Dc and ac
DC only
AC only
Neither dc nor ac
The ac collector current is approximately equal to the
AC base current
AC emitter current
AC source current
AC bypass current
The ac emitter current times the ac emitter resistance equals the
Dc emitter voltage
AC base voltage
AC collector voltage
Supply voltage
The ac collector current equals the ac base current times the
AC collector resistance
DC current gain
AC current gain
Generator voltage
The emitter is at ac ground in a
CB stage
CC stage
CE stage
None of these
The output voltage of a CE stage is usually
Constant
Dependent on re’
Small
Less the one
The voltage gain equals the output voltage divided by the
Input voltage
AC emitter resistance
AC collector resistance
Generator voltage
The input impedance of the base increases when
Beta increases
Supply voltage increases
Supply voltage increases
AC collector resistance increases
Voltage gain is directly proportional to
Beta
Ac emitter resistance
. DC collector voltage
AC collector resistance
Compared to the ac resistance of the emitter diode, the feedback resistance of a swamped amplifier should be
Small
Equal
Large
Zero
Compared to a CE stage, a swamped amplifier has an input impedance that is
Smaller
Equal
Larger
Zero
To reduce the distortion of an amplified signal, you can increase the
Collector resistance
Emitter feedback resistance
Generator resistance
Load resistance
The emitter of a swamped amplifier
Is grounded
Has no dc voltage
Has an ac voltage
Has no ac voltage
A swamped amplifier uses
Base bias
Positive feedback
Negative feedback
A grounded emitter
In a swamped amplifier, the effects of the emitter diode become
Important to voltage gain
Critical to input impedance
Significant to the analysis
Unimportant
The feedback resistor
Increases voltage gain
Reduces distortion
Decreases collector resistance
Decreases input impedance
The feedback resistor
Stabilizes voltage gain
Increases distortion
Increases collector resistance
Decreases input impedance
The ac collector resistance of the first stage includes the
Load resistance
Input impedance of first stage
Emitter resistance of first stage
Input impedance of second stage
If the emitter bypass capacitor opens, the ac output voltage will
Decrease
Increase
Remain the same
Equal zero
If the collector resistor is shorted, the ac output voltage will
Decrease
Increase
Remain the same
Equal zero
If the load resistance is open, the ac output voltage will
Decrease
Increase
Remain the same
Equal zero
If any capacitor is open, the ac output voltage will
Decrease
Increase
Remain the same
Equal zero
If the input coupling capacitor is open, the ac input voltage will
Decrease
Increase
Remain the same
Equal zero
If the bypass capacitor is open, the ac input voltage will
Decrease
Increase
Remain the same
Equal zero
If the output coupling capacitor is open, the ac input voltage will
Decrease
Increase
Remain the same
Equal zero
If the emitter resistor is open, the ac input voltage will
Decrease
Increase
Remain the same
Equal zero
If the collector resistor is open, the ac input voltage will
Decrease
Increase
Remain the same
Equal approximately zero
If the emitter bypass capacitor is shorted, the ac input voltage will
Decrease
Increase
Remain the same
Equal zero
For class B operation, the collector current flows
The whole cycle
Half the cycle
Less than half a cycle
Less than a quarter of a cycle
Transformer coupling is an example of
Direct coupling
AC coupling
DC coupling
Impedance coupling
An audio amplifier operates in the frequency range of
0 to 20 Hz
20 Hz to 20 kHz
20 to 200 kHz
Above 20 kHz
A tuned RF amplifier is
Narrowband
Wideband
Direct coupled
Impedance coupled
The first stage of a preamp is
A tuned RF stage
Large signal
Small signal
A dc amplifier
For maximum peak-to-peak output voltage, the Q point should be
Near saturation
Near cutoff
At the center of the dc load line
At the center of the ac load line
An amplifier has two load lines because
It has ac and dc collector resistances
It has two equivalent circuits
DC acts one way and ac acts another
All of the above
When the Q point is at the center of the ac load line, the maximum peak-to-peak output voltage equals
VCEQ
2VCEQ
ICQ
2IcQ
Push-pull is almost always used with
Class A
Class B
Class C
All of the above
One advantage of a class B push-pull amplifier is
ery small quiescent current drain
aximum efficiency of 78.5 percent
reater efficiency than class A
All of the above
Class C amplifiers are almost always
Transformer-coupled between stages
Operated at audio frequencies
Tuned RF amplifiers
Wideband
The input signal of a class C amplifier
Is negatively clamped at the base
Is amplified and inverted
Produces brief pulses of collector current
All of the above
The collector current of a class C amplifier
Is an amplified version of the input voltage
Has harmonics
Is negatively clamped
Is negatively clamped
The bandwidth of a class C amplifier decreases when the
Resonant frequency increases
Q increases
XL decreases
Load resistance decreases
The transistor dissipation in a class C amplifier decreases when the
Resonant frequency increases
coil Q increases
Load resistance decreases
Capacitance increases
The power rating of a transistor can be increased by
Raising the temperature
Using a heat sink
Using a derating curve
Operating with no input signal
The ac load line is the same as the dc load line when the ac collector resistance equals the
DC emitter resistance
AC emitter resistance
DC collector resistance
Supply voltage divided by collector current
If RC = 3.6 kohm and RL = 10 kohm, the ac load resistance equals
10 kohm
2.65 kohm
I kohm
3.6 kohm
The quiescent collector current is the same as the
DC collector current
AC collector current
Total collector current
Voltage-divider current
The ac load line usually
Equals the dc load line
Has less slope than the dc load line
Is steeper than the dc load line
Is horizontal
For a Q point near the center of the dc load line, clipping is more likely to occur on the
Positive peak of input voltage
Negative peak of output voltage
Positive peak of output voltage
Negative peak of emitter voltage
In a class A amplifier, the collector current flows for
Less than half the cycle
Half the cycle
Less than the whole cycle
The entire cycle
With class A, the output signal should be
Unclipped
Clipped on positive voltage peak
Clipped on negative voltage peak
lipped on negative current peak
The instantaneous operating point swings-along the
AC load line
DC load line
Both load lines
Neither load line
The current drain of an amplifier is the
Total ac current from the generator
Total dc current from the supply
Current gain from base to collector
Current gain from collector to base
The power gain of an amplifier
Is the same as the voltage gain
Is smaller than the voltage gain
Equals output power divided by input power
Equals load power
Heat sinks reduce the
Transistor power
Ambient temperature
Junction temperature
Collector current
When the ambient temperature increases, the maximum transistor power rating
Decreases
Increases
Remains the same
None of the above
If the load power is 3 mW and the dc power is 150 mW, the efficiency is
0
2 percent
3 percent
20 percent
