E6 Questions
62 questions in this subelement. Click any question ID for more details.
Answer: A
Which of the following semiconductor materials contains excess free electrons?
AN-type
BP-type
CBipolar
DInsulated gate
Answer: C
Why does a PN-junction diode not conduct current when reverse biased?
AOnly P-type semiconductor material can conduct current
BOnly N-type semiconductor material can conduct current
CHoles in P-type material and electrons in the N-type material are separated by the applied voltage, widening the depletion region
DExcess holes in P-type material combine with the electrons in N-type material, converting the entire diode into an insulator
Answer: C
What is the name given to an impurity atom that adds holes to a semiconductor crystal structure?
AInsulator impurity
BN-type impurity
CAcceptor impurity
DDonor impurity
Answer: C
How does DC input impedance at the gate of a field-effect transistor (FET) compare with that of a bipolar transistor?
AThey are both low impedance
BAn FET has lower input impedance
CAn FET has higher input impedance
DThey are both high impedance
Answer: B
What is the beta of a bipolar junction transistor?
AThe frequency at which the current gain is reduced to 0.707
BThe change in collector current with respect to the change in base current
CThe breakdown voltage of the base-to-collector junction
DThe switching speed
Answer: D
Which of the following indicates that a silicon NPN junction transistor is biased on?
ABase-to-emitter resistance of approximately 6 ohms to 7 ohms
BBase-to-emitter resistance of approximately 0.6 ohms to 0.7 ohms
CBase-to-emitter voltage of approximately 6 volts to 7 volts
DBase-to-emitter voltage of approximately 0.6 volts to 0.7 volts
Answer: D
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?
ACorner frequency
BAlpha rejection frequency
CBeta cutoff frequency
DAlpha cutoff frequency
Answer: A
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
BAn FET that has no current flow between source and drain when no gate voltage is applied
CAn FET that exhibits very high electron mobility due to a lack of holes in the N-type material
DAn FET for which holes are the majority carriers
Answer: B
In Figure E6-1, which is the schematic symbol for an N-channel dual-gate MOSFET?
A2
B4
C5
D6
Answer: D
What is the purpose of connecting Zener diodes between a MOSFET gate and its source or drain?
ATo provide a voltage reference for the correct amount of reverse-bias gate voltage
BTo protect the substrate from excessive voltages
CTo keep the gate voltage within specifications and prevent the device from overheating
DTo protect the gate from static damage
Answer: D
Which characteristic of a Schottky diode makes it a better choice than a silicon junction diode for use as a power supply rectifier?
AMuch higher reverse voltage breakdown
BMore constant reverse avalanche voltage
CLonger carrier retention time
DLower forward voltage drop
Answer: B
What property of an LED's semiconductor material determines its forward voltage drop?
AIntrinsic resistance
BBand gap
CJunction capacitance
DJunction depth
Answer: A
What type of semiconductor device is designed for use as a voltage-controlled capacitor?
AVaractor diode
BTunnel diode
CSilicon-controlled rectifier
DZener diode
Answer: D
What characteristic of a PIN diode makes it useful as an RF switch?
AExtremely high reverse breakdown voltage
BAbility to dissipate large amounts of power
CReverse bias controls its forward voltage drop
DLow junction capacitance
Answer: D
Which of the following is a common use of a Schottky diode?
AIn oscillator circuits as the negative resistance element
BAs a variable capacitance in an automatic frequency control circuit
CIn power supplies as a constant voltage reference
DAs a VHF/UHF mixer or detector
Answer: B
What causes a junction diode to fail from excessive current?
AExcessive inverse voltage
BExcessive junction temperature
CInsufficient forward voltage
DCharge carrier depletion
Answer: A
Which of the following is a Schottky barrier diode?
AMetal-semiconductor junction
BElectrolytic rectifier
CPIN junction
DThermionic emission diode
Answer: C
What is a common use for point-contact diodes?
AAs a constant current source
BAs a constant voltage source
CAs an RF detector
DAs a high-voltage rectifier
Answer: A
What is used to control the attenuation of RF signals by a PIN diode?
AForward DC bias current
BA variable RF reference voltage
CReverse voltage larger than the RF signal
DCapacitance of an RF coupling capacitor
Answer: B
What happens when the level of a comparator’s input signal crosses the threshold voltage?
AThe IC input can be damaged
BThe comparator changes its output state
CThe reference level appears at the output
DThe feedback loop becomes unstable
Answer: A
What is tri-state logic?
ALogic devices with 0, 1, and high-impedance output states
BLogic devices that utilize ternary math
CLogic with three output impedances which can be selected to better match the load impedance
DA counter with eight states
Answer: C
Which of the following is an advantage of BiCMOS logic?
AIts simplicity results in much less expensive devices than standard CMOS
BIt is immune to electrostatic damage
CIt has the high input impedance of CMOS and the low output impedance of bipolar transistors
DAll these choices are correct
Answer: D
Which of the following digital logic families has the lowest power consumption?
ASchottky TTL
BECL
CNMOS
DCMOS
Answer: C
Why do CMOS digital integrated circuits have high immunity to noise on the input signal or power supply?
ALarge bypass capacitance is inherent
BThe input switching threshold is about twice the power supply voltage
CThe input switching threshold is about half the power supply voltage
DBandwidth is very limited
Answer: B
What best describes a pull-up or pull-down resistor?
AA resistor in a keying circuit used to reduce key clicks
BA resistor connected to the positive or negative supply used to establish a voltage when an input or output is an open circuit
CA resistor that ensures that an oscillator frequency does not drift
DA resistor connected to an op-amp output that prevents signals from exceeding the power supply voltage
Answer: B
What is used to design the configuration of a field-programmable gate array (FPGA)?
AKarnaugh maps
BHardware description language (HDL)
CAn auto-router
DMachine and assembly language
Answer: C
In Figure E6-3, which is the schematic symbol for the NOT operation (inversion)?
A2
B4
C5
D6
Answer: A
What is the equivalent circuit of a quartz crystal?
ASeries RLC in parallel with a shunt C representing electrode and stray capacitance
BParallel RLC, where C is the parallel combination of resonance capacitance of the crystal and electrode and stray capacitance
CSeries RLC, where C is the parallel combination of resonance capacitance of the crystal and electrode and stray capacitance
DParallel RLC, where C is the series combination of resonance capacitance of the crystal and electrode and stray capacitance
Answer: A
Which of the following is an aspect of the piezoelectric effect?
AMechanical deformation of material due to the application of a voltage
BMechanical deformation of material due to the application of a magnetic field
CGeneration of electrical energy in the presence of light
DIncreased conductivity in the presence of light
Answer: B
Why are cores of inductors and transformers sometimes constructed of thin layers?
ATo simplify assembly during manufacturing
BTo reduce power loss from eddy currents in the core
CTo increase the cutoff frequency by reducing capacitance
DTo save cost by reducing the amount of magnetic material
Answer: C
How do ferrite and powdered iron compare for use in an inductor core?
AFerrite cores generally have lower initial permeability
BFerrite cores generally have better temperature stability
CFerrite cores generally require fewer turns to produce a given inductance value
DFerrite cores are easier to use with surface-mount technology
Answer: D
What core material property determines the inductance of an inductor?
APermittivity
BResistance
CReactivity
DPermeability
Answer: B
Which of the following materials has the highest temperature stability of its magnetic characteristics?
ABrass
BPowdered iron
CFerrite
DAluminum
Answer: C
What devices are commonly used as VHF and UHF parasitic suppressors at the input and output terminals of a transistor HF amplifier?
AElectrolytic capacitors
BButterworth filters
CFerrite beads
DSteel-core toroids
Answer: A
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
BToroidal cores make it easier to couple the magnetic energy into other components
CToroidal cores exhibit greater hysteresis
DToroidal cores have lower Q characteristics
Answer: B
Which type of core material decreases inductance when inserted into a coil?
ACeramic
BBrass
CFerrite
DAluminum
Answer: C
What causes inductor saturation?
AOperation at too high a frequency
BSelecting a core with low permeability
COperation at excessive magnetic flux
DSelecting a core with excessive permittivity
Answer: D
Which of the following materials supports the highest frequency of operation when used in MMICs?
ASilicon
BSilicon nitride
CSilicon dioxide
DGallium nitride
Answer: A
Which is the most common input and output impedance of MMICs?
A50 ohms
B300 ohms
C450 ohms
D75 ohms
Answer: A
Which of the following noise figure values is typical of a low-noise UHF preamplifier?
A0.5 dB
B-10 dB
C44 dBm
D-20 dBm
Answer: D
What characteristics of MMICs make them a popular choice for VHF through microwave circuits?
AThe ability to retrieve information from a single signal, even in the presence of other strong signals
BExtremely high Q factor and high stability over a wide temperature range
CNearly infinite gain, very high input impedance, and very low output impedance
DControlled gain, low noise figure, and constant input and output impedance over the specified frequency range
Answer: D
What type of transmission line is often used for connections to MMICs?
AMiniature coax
BCircular waveguide
CParallel wire
DMicrostrip
Answer: C
How is power supplied to the most common type of MMIC?
AThrough a capacitor and RF choke connected to the amplifier input lead
BMMICs require no operating bias
CThrough a resistor and/or RF choke connected to the amplifier output lead
DDirectly to the bias voltage (Vcc) lead
Answer: D
Which of the following component package types have the least parasitic effects at frequencies above the HF range?
ATO-220
BAxial lead
CRadial lead
DSurface mount
Answer: D
What advantage does surface-mount technology offer at RF compared to using through-hole components?
ASmaller circuit area
BShorter circuit board traces
CComponents have less parasitic inductance and capacitance
DAll these choices are correct
Answer: D
What is a characteristic of DIP packaging used for integrated circuits?
AExtremely low stray capacitance (dielectrically isolated package)
BExtremely high resistance between pins (doubly insulated package)
CTwo chips in each package (dual in package)
DTwo rows of connecting pins on opposite sides of package (dual in-line package)
Answer: C
Why are DIP through-hole package ICs not typically used at UHF and higher frequencies?
AExcessive dielectric loss
BEpoxy coating is conductive above 300 MHz
CExcessive lead length
DUnsuitable for combining analog and digital signals
Answer: A
What happens to photoconductive material when light shines on it?
AResistance decreases
BResistance increases
CReflectivity increases
DReflectivity decreases
Answer: D
What is the most common configuration of an optoisolator or optocoupler?
AA lens and a photomultiplier
BA frequency-modulated helium-neon laser
CAn amplitude-modulated helium-neon laser
DAn LED and a phototransistor
Answer: B
What is the photovoltaic effect?
AThe conversion of voltage to current when exposed to light
BThe conversion of light to electrical energy
CThe effect that causes a photodiode to emit light when a voltage is applied
DThe effect that causes a phototransistor’s beta to decrease when exposed to light
Answer: A
Which of the following describes an optical shaft encoder?
AA device that detects rotation by interrupting a light source with a patterned wheel
BA device that measures the strength of a beam of light using analog-to-digital conversion
CAn optical computing device in which light is coupled between devices by fiber optics
DA device for generating RTTY signals by means of a rotating light source
Answer: C
Which of these materials is most commonly used to create photoconductive devices?
APolyphenol acetate
BArgon
CCrystalline semiconductor
DAll these choices are correct
Answer: B
What is a solid-state relay?
AA relay that uses transistors to drive the relay coil
BA device that uses semiconductors to implement the functions of an electromechanical relay
CA mechanical relay that latches in the on or off state each time it is pulsed
DA semiconductor switch that uses a monostable multivibrator circuit
Answer: C
Why are optoisolators often used in conjunction with solid-state circuits that control 120 VAC circuits?
AOptoisolators provide a low-impedance link between a control circuit and a power circuit
BOptoisolators provide impedance matching between the control circuit and power circuit
COptoisolators provide an electrical isolation between a control circuit and the circuit being switched
DOptoisolators eliminate the effects of reflected light in the control circuit
Answer: D
What is the efficiency of a photovoltaic cell?
AThe output RF power divided by the input DC power
BThe output in lumens divided by the input power in watts
CThe open-circuit voltage divided by the short-circuit current under full illumination
DThe relative fraction of light that is converted to current
Answer: B
What is the most common material used in power-generating photovoltaic cells?
ASelenium
BSilicon
CCadmium sulfide
DIndium arsenide
Answer: A
What is the approximate open-circuit voltage produced by a fully illuminated silicon photovoltaic cell?
A0.5 volts
B0.7 volts
C1.1 volts
D1.5 volts