In what application is gallium arsenide used as a semiconductor material?
CIn microwave circuits
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Subelement E6 question review
All 68 official questions with the exact winning phrase marked.
Which of the following semiconductor materials contains excess free electrons?
AN-type
Why does a PN-junction diode not conduct current when reverse biased?
CHoles in P-type material and electrons in the N-type material are separated by the applied voltage, widening the depletion region
What is the name given to an impurity atom that adds holes to a semiconductor crystal structure?
CAcceptor impurity
How does DC input impedance at the gate of a field-effect transistor (FET) compare with that of a bipolar transistor?
CAn FET has higher input impedance
What is the beta of a bipolar junction transistor?
BThe change in collector current with respect to the change in base current
Which of the following indicates that a silicon NPN junction transistor is biased on?
DBase-to-emitter voltage of approximately 0.6 volts to 0.7 volts
What is the term for the frequency at which the grounded-base current gain of a bipolar junction transistor has decreased to 0.7 of the gain obtainable at 1 kHz?
DAlpha cutoff frequency
What is a depletion-mode field-effect transistor (FET)?
AAn FET that exhibits a current flow between source and drain when no gate voltage is applied
In Figure E6-1, which is the schematic symbol for an N-channel dual-gate MOSFET?
B4
In Figure E6-1, which is the schematic symbol for a P-channel junction FET?
A1
What is the purpose of connecting Zener diodes between a MOSFET gate and its source or drain?
DTo protect the gate from static damage
What is the most useful characteristic of a Zener diode?
BA constant voltage drop under conditions of varying current
Which characteristic of a Schottky diode makes it a better choice than a silicon junction diode for use as a power supply rectifier?
DLower forward voltage drop
What property of an LED's semiconductor material determines its forward voltage drop?
BBand gap
What type of semiconductor device is designed for use as a voltage-controlled capacitor?
AVaractor diode
What characteristic of a PIN diode makes it useful as an RF switch?
DLow junction capacitance
Which of the following is a common use of a Schottky diode?
DAs a VHF/UHF mixer or detector
What causes a junction diode to fail from excessive current?
BExcessive junction temperature
Which of the following is a Schottky barrier diode?
AMetal-semiconductor junction
What is a common use for point-contact diodes?
CAs an RF detector
In Figure E6-2, which is the schematic symbol for a Schottky diode?
B6
What is used to control the attenuation of RF signals by a PIN diode?
AForward DC bias current
What is the function of hysteresis in a comparator?
ATo prevent input noise from causing unstable output signals
What happens when the level of a comparator’s input signal crosses the threshold voltage?
BThe comparator changes its output state
What is tri-state logic?
ALogic devices with 0, 1, and high-impedance output states
Which of the following is an advantage of BiCMOS logic?
CIt has the high input impedance of CMOS and the low output impedance of bipolar transistors
Which of the following digital logic families has the lowest power consumption?
DCMOS
Why do CMOS digital integrated circuits have high immunity to noise on the input signal or power supply?
CThe input switching threshold is about half the power supply voltage
What best describes a pull-up or pull-down resistor?
BA resistor connected to the positive or negative supply used to establish a voltage when an input or output is an open circuit
In Figure E6-3, which is the schematic symbol for a NAND gate?
B2
What is used to design the configuration of a field-programmable gate array (FPGA)?
BHardware description language (HDL)
In Figure E6-3, which is the schematic symbol for a NOR gate?
D4
In Figure E6-3, which is the schematic symbol for the NOT operation (inversion)?
C5
What is piezoelectricity?
CA characteristic of materials that generate a voltage when stressed and that flex when a voltage is applied
What is the equivalent circuit of a quartz crystal?
ASeries RLC in parallel with a shunt C representing electrode and stray capacitance
Which of the following is an aspect of the piezoelectric effect?
AMechanical deformation of material due to the application of a voltage
Why are cores of inductors and transformers sometimes constructed of thin layers?
BTo reduce power loss from eddy currents in the core
How do ferrite and powdered iron compare for use in an inductor core?
CFerrite cores generally require fewer turns to produce a given inductance value
What core material property determines the inductance of an inductor?
DPermeability
Which of the following materials has the highest temperature stability of its magnetic characteristics?
BPowdered iron
What devices are commonly used as VHF and UHF parasitic suppressors at the input and output terminals of a transistor HF amplifier?
CFerrite beads
What is a primary advantage of using a toroidal core instead of a solenoidal core in an inductor?
AToroidal cores confine most of the magnetic field within the core material
Which type of core material decreases inductance when inserted into a coil?
BBrass
What causes inductor saturation?
COperation at excessive magnetic flux
Why is gallium arsenide (GaAs) useful for semiconductor devices operating at UHF and higher frequencies?
BHigher electron mobility
Which of the following device packages is a through-hole type?
ADIP
Which of the following materials supports the highest frequency of operation when used in MMICs?
DGallium nitride
Which is the most common input and output impedance of MMICs?
A50 ohms
Which of the following noise figure values is typical of a low-noise UHF preamplifier?
A0.5 dB
What characteristics of MMICs make them a popular choice for VHF through microwave circuits?
DControlled gain, low noise figure, and constant input and output impedance over the specified frequency range
What type of transmission line is often used for connections to MMICs?
DMicrostrip
How is power supplied to the most common type of MMIC?
CThrough a resistor and/or RF choke connected to the amplifier output lead
Which of the following component package types have the least parasitic effects at frequencies above the HF range?
DSurface mount
What advantage does surface-mount technology offer at RF compared to using through-hole components?
DAll these choices are correct
What is a characteristic of DIP packaging used for integrated circuits?
DTwo rows of connecting pins on opposite sides of package (dual in-line package)
Why are DIP through-hole package ICs not typically used at UHF and higher frequencies?
CExcessive lead length
What absorbs the energy from light falling on a photovoltaic cell?
CElectrons
What happens to photoconductive material when light shines on it?
AResistance decreases
What is the most common configuration of an optoisolator or optocoupler?
DAn LED and a phototransistor
What is the photovoltaic effect?
BThe conversion of light to electrical energy
Which of the following describes an optical shaft encoder?
AA device that detects rotation by interrupting a light source with a patterned wheel
Which of these materials is most commonly used to create photoconductive devices?
CCrystalline semiconductor
What is a solid-state relay?
BA device that uses semiconductors to implement the functions of an electromechanical relay
Why are optoisolators often used in conjunction with solid-state circuits that control 120 VAC circuits?
COptoisolators provide an electrical isolation between a control circuit and the circuit being switched
What is the efficiency of a photovoltaic cell?
DThe relative fraction of light that is converted to current
What is the most common material used in power-generating photovoltaic cells?
BSilicon
What is the approximate open-circuit voltage produced by a fully illuminated silicon photovoltaic cell?
A0.5 volts