Ch 5 & 6
Determine the load resistance that will dissipate the most power when connected to a signal source with an impedance of 1 kOhm.
1 kOhm
Using 0.7 volts for Vce, find the emitter voltage. (question 29 on chapter 6 worksheet)
1.87 V
The output level of an amplifier is specified as +40 dBm. What is this level in watts?
10 W
An amplifier has an input of 50 mV and an output of 5 V. Find its voltage gain
100
Find beta in a transistor when the collector current is 10 mA and the emitter current is 10.1 mA.
100
Find the base current in a transistor when the collector current is 10 mA and the emitter current is 10.1 mA.
100 uA
Using 0.7 volts for Vbe, find the collector current (question 17 on chapter 6 worksheet)
12.8 mA
The signal fed into an amplifier is 0.1 volts and the output signal is 15 volts. What is the proper way of expressing the voltage gain of this amplifier?
150
What is the ratio power gain of an amplifier that produces 150 watts of output for 1 watt of input?
150
Assuming the signal source has a low internal resistance for dc, find Vce if the coupling capacitor is shorted. (question 19 on chapter 6 worksheet)
18.0 volts
phase relationship of amplifier (question 15 on chapter 6 worksheet)
180 degrees
What is the output signal from an amplifier with a voltage gain of 25 and an input signal of 85 mV?
2.13 V
Using 0.7 volts for Vbe and 50 mV for re, find the voltage gain for this amplifier. (question 32 on chapter 6 worksheet)
2.45
What is the decibel power gain of an amplifier that produces 150 watts of output for 1 watt of input?
21.8 dB
A three stage system has a first stage gain of 6 dB, a second stage gain of 8 dB, and a third stage gain of 10 dB. What is the dB gain of the entire system?
24 dB
A three stage system has a first stage gain of 6 dB, a second stage gain of 8 dB, and a third stage gain of 10 dB. What is the ratio gain of the entire system?
251
Find a value for Rb to operate the amplifier at the center of its load line assuming Vbe is 0.7 V. (question 24 on chapter 6 worksheet)
277 kOhms
A transistor has a beta of 150. Find the collector current when the base current is 25 uA.
3.75 mA
Know what a VMOS device looks like (question 38 on ch5 worksheet) answer is 4 btw
4
A three stage system has ratio power gains of 80 in the first stage, 17 in the second stage, and 40 in the third stage. What is the dB system gain?
47.4
Calculate the collector dissipation in a transistor when the base current is 500 uA, beta is 170, and the voltage from collector to emitter is 12 volts.
6 mW
Using 0.7 volts for Vbe, find the base current (question 16 on chapter 6 worksheet)
64.1 uA
Using 0.7 volts for Vbe, find Vce. (question 30 on chapter 6 worksheet)
7.42 V
The voltage gain of a circuit is -3 dB. What is the output voltage for this circuit when the input is one volt?
708 mV
An amplifier with a voltage gain of 100 and a current gain of 0.8 has a power gain of
80
Using 0.7 volts for Vbe, find Vc. (question 31 on chapter 6 worksheet)
9.29 V
Using 0.7 volts for Vbe, find the collector to emitter voltage (question 18 on chapter 6 worksheet)
9.29 volts
What is the power gain of an amplifier that has a voltage gain of 1.5 and a current gain of 60?
90
Using 0.7 volts for Vbe and 50 mV for re, find the voltage gain for this amplifier when the switch is closed. (question 33 on chapter 6 worksheet)
94.3
A three stage system has ratio voltage gains of 80 in the first stage, 17 in the second stage, and 40 in the third stage. Assuming equal input and output resistance, what is the dB system gain?
94.7
A graph of Vce versus Ic for several fixed values of Ib is called
A collector family of curves
Using a circuit simulator to predict circuit behavior at ten different temperatures is an example of
A parameter sweep
In an ideal bipolar switching transistor, the collector dissipation is zero when
All of the above (ib is high, ic=0, vce=0)
_____ make sounds louder and signal levels better.
Amplifiers
The current gain of a bipolar junction transistor is specified as ______.
Beta
Motors usually generate a large____ when they are switched off.
CEMF
In transistor gain formulas, the symbol /\ means
Change in
Answer is common collector configuration (question 35 on chapter 6 worksheet)
Common collector configuration
What kind of amplifier. Answer is common emitter (question 14 on chapter 6 worksheet)
Common emitter
Which amplifier configuration provides both voltage and current gain and also provides the best power gain?
Common emitter
Troubleshooting this amplifier reveals that Vce is -9 volts. The circuit is in (question 28 on chapter 6 worksheet)
Cutoff
What type of transistor does this symbol represent?
Darlington
________ transistor testing reveals power gain and noise figure under signal conditions.
Dynamic
Testing a transistor while it operates with real voltages and signals is referred to as
Dynamic testing
If an amplifier provides an output voltage that is 100 times greater than the input voltage, the gain of the amplifier is 10.
False (10 times greater than the input voltage)
The PNP transistor is more widely used than the NPN transistor
False (NPN more widely used)
The schematic diagram of an NPN bipolar junction transistor shows the emitter lead as an arrow pointing in.
False (NPN points out)
In the bipolar junction transistor, the collector sends carriers into the base and then on to the emitter.
False (emitter to base to collector)
With transistor bias, the collector-base junction must be forward-biased for proper operation.
False (must be reversed-biased)
In electronics, gain is expressed in volts, amperes, or watts.
False (not expressed in volts, amps, or watts)
The base-emitter junction of a BJT must be ______ to turn the transistor on.
Forward biased
_______ is the ratio of some output to some input.
Gain
With bipolar junction transistors, the frequency at which the ac current gain drops to 1 is the
Gain-bandwidth product
Answer is gate (know the terminals)
Gate
When using a DMM to test a transistor and the junction tested is reverse-biased, the reading will be
Greater than 20 MegaOhms (over range)
This amplifier (question 36 on chapter 6 worksheet)
Has a low output impedance
What is this?
Insulated gate bipolar transistor (igbt)
What is a major shortcoming of this amplifier? (question 22 on chapter 6 worksheet)
It is beta dependent
When an equation can't be solved, a process of repeated guessing can be used. This process is called
Iteration
Which is the following operates in the depletion mode?
JFET
Which of the following is a unipolar device?
Junction field-effect transistor
Transistor _______ current is due to minority carriers action
Leakage
The response of human hearing for loudness
Logarithmic
Which of the following is a reason why a germanium transistor might be used instead of a silicon transistor?
Low turn-on voltage
Which of the following qualifies as a voltage controlled device?
MOSFET
Which of the following is not a limitation of a bipolar power transistor?
Minority carrier speed limiters
What is this?
N-channel JFET
BJTs are manufactured in two basic forms:
NPN and PNP
Bipolar power transistors are an older technology but can be favored over VFETs because they
Often cost less
An IC that contains a diode and transistor that are optically coupled is a(n)
Optoisolator
It is not appropriate to measure the gain of a linear amplifier when its input is
Overdriven
What is this?
PNP transistor
What type of transistor can be manufactured without a base lead?
Phototransistor
Only amplifiers provide a ____ gain.
Power
An amplifier that develops a large signal is referred to as a
Power amp
What type of waveform is most likely to be found at the input of a switching transistor?
Rectangle
For a given amplifier, the dB voltage gain will be equal to the dB power gain only when
Rin is equal to Rout
Troubleshooting this amplifier reveals that Vce is near 0 volts. The circuit is in (question 26 on chapter 6 worksheet)
Saturation
SPICE stands for
Simulation Program with IC Emphasis
The drive waveforms supplied to a stepper motor are
Sine
Which of the following is generally the least efficient method of locating bad transistors?
Substitute known good transistors
A technician can learn something about a particular transistor by using a(n) __________ guide.
Substitution
The usual failure mode for BJTs is
Sudden and total
Common logarithms are powers (exponents) of
Ten
Which of the following is a true statement?
The BJT is normally on
The gate current in a normally operating JFET is zero because
The gate-source junction is reverse biased
Troubleshooting this amplifier reveals that Vce is 5.2 volts. The circuit is in (question 27 on chapter 6 worksheet)
The linear region
Why is the supply voltage negative? (question 25 on chapter 6 worksheet)
The transistor is PNP
When ohmmeter testing a silicon NPN transistor, the positive lead is in contact with the collector, the negative lead is in contact with the emitter, and the meter shows a high but not infinite resistance
This is normal for silicon transistors
________ characteristic curves show how one transistor terminal affects another.
Transfer
A step-up transformer provides voltage gain.
True
Amplifiers provide a function called gain.
True
In a BJT, the base-emitter junction must be forward-biased for the emitter to emit.
True
Only amplifiers provide a power gain.
True
The most popular transistor type is the bipolar junction transistor.
True
There is no significant difference between ßa and ßac at low frequencies.
True
A transistor is said to be saturated when it is
Turned on hard
A transistor that operates in a negative-resistance region and is used for timing and control is the
UJT
What is this called?
UJT
Which of the following transistors is not useful as an amplifier?
Unijunction transistor
Which of the following transistors shows a negative resistance region of operation?
Unijunction transistor
The junction field-effect transistor is a(n) _________ transistor.
Unipolar
Which of the following is not a method of testing a transistor in-circuit?
Using a signal generator
A transistor that has a vertical current flow, a wide, short channel with a very low resistance is the
VFET
An analysis of this amplifier shows that the amplifier is biased for linear service because: (question 20 on chapter 6 worksheet)
Vce is approximately half of the supply voltage
In an ideal bipolar switching transistor, the collector dissipation is zero when the transistor is on because
Vce=0
Failures of switching transistors can sometimes be attributed to not enough drive ______.
Voltage
When ohmmeter testing a BJT with no known part number, you
can identify polarity, all leads, and verify gain
The basic function of the base of a BJT is to
control the flow of current carriers
The drain characteristic curves for an N-channel JFET show that
drain current decreases as Vgs becomes more negative
When a change in collector current (/\Ic) is divided by the corresponding change in base current (/\Ib), the result is called
gain-bandwidth product
MOSFETs can operate in the enhancement mode without gate current because they
have a silicon dioxide layer between gate and channel
VFETs have a low on-resistance which
makes them efficient switching devices
Assuming a voltage gain of 180, will the output of this amplifier be clipped? (question 21 on chapter 6 worksheet)
no, it will be about 10.2 Volts peak-to-peak
Which of the following junction bias conditions produces normal (linear) transistor operation?
reverse bias on C-B and forward on E-B
Transformers are not considered amplifiers because
their power gain is always less than one
BJTs have
two P-N junctions
