Chapter 5 Components and Building Blocks

Chapter 5 Components and Building Blocks

Semiconductor Devices
Materials Atomic Structure. Nucleus (Protons & Neutrons). Electrons. Orbits (Shells). Valence electrons. 8 Valence electrons completes a shell. Atomic number. Number of protons in nucleus. Number of electrons (non-ionized).

Materials Electrons in outer shell are called valence electrons. Valence electrons allow atoms to interact with other atoms to form compounds. Atoms want to have their outer shell of electrons filled. Full shell = 8 electrons. Atoms can share valence electrons with other atoms to fill their outer shell forming a compound.

Materials Atoms with fewer than 4 valence electrons are normally conductors (metals). Atoms with more than 4 valence electrons are normally non-conductors. Atoms with 4 valence electrons are normally semi-conductors. Silicon Germanium

Materials Atoms can arrange themselves into a regular pattern by sharing valence electrons to form a crystal. Crystals of pure silicon (Si) or germanium (Ge) are not normally good conductors.

Materials Crystals of pure semi-conductor atoms, such as silicon (Si), can have a precisely controlled number of other atoms inserted into the crystal structure. This process is called “doping”. Doping with atoms with 3 or 5 valence electrons causes the crystal to become more conductive.

Materials Adding an element with 5 valence electrons (donor impurity) creates N-type material. Excess free electrons. Typical donor impurities: Arsenic Antimony Phosphorus

Materials Adding an element with 3 valence electrons (acceptor impurity) creates P-type material. Shortage of free electrons (holes). Typical acceptor impurities: Aluminum Gallium Indium

Materials Majority Charge Carriers. N-Type Material = Electron P-Type Material = Hole Other semiconductor materials. Gallium-Arsenide (GaAs). LED’s Microwave frequencies. Gallium-Arsenide-Phosphide (GaAsP).

E6A02 -- Which of the following semiconductor materials contains excess free electrons?
N-type P-type Bipolar Insulated gate

E6A04 -- What is the name given to an impurity atom that adds holes to a semiconductor crystal structure? Insulator impurity N-type impurity Acceptor impurity Donor impurity

E6A15 -- Which semiconductor material contains excess holes in the outer shell of electrons?
N-type P-type Superconductor-type Bipolar-type

E6A16 -- What are the majority charge carriers in N-type semiconductor material?
Holes Free electrons Free protons Free neutrons

Diodes A diode allows current flow in one direction and resists current flow in the other direction. Two terminals: Anode Cathode. Electrons flow from cathode to anode. Holes flow from anode to cathode.

Diodes Junction diodes. With no voltage applied, electrons & holes combine at the junction forming a depletion region.

Diodes Junction diodes. A positive voltage applied to anode will attract electrons in N-type material. Depletion area collapses. Electrons flow from N-type material to P-type material.

Diodes Junction diodes. Forward Voltage Drop – Minimum forward voltage required for current to flow. Silicon = 0.7 Volts (approx.) Germanium = 0.3 Volts (approx.) GaAs & GaAsP = 1.2 Volts to 1.5 Volts (approx.)

Diodes Junction diodes. A negative voltage applied to anode will repel electrons in N-type material. Depletion area gets wider. No electron flow.

Diodes Diode Ratings. Peak Inverse Voltage (PIV). Avalanche voltage. Maximum Average Forward Current. Maximum Allowable Junction Temperature.

Diodes Schottky Barrier Diodes. P-type material replaced with a layer of metal. Point-Contact Diodes. Hot-Carrier Diodes. Lower forward voltage drop. Less power dissipation. Power supplies.

Diodes Point-Contact Diodes. Very low junction capacitance. Very low current. Better for VHF & UHF detectors than normal junction diode.

Diodes Hot-Carrier Diodes. Similar to point-contact diode. More stable mechanically. Lower contact resistance  Higher current capability.

Diodes Zener Diodes. Operates with reverse bias. Operates at avalanche voltage. Large change in avalanche current results in small change in voltage. Designed to withstand avalanche current with proper heat sink.

Diodes Tunnel Diodes. Special type of diode that does not rectify. When properly biased, exhibits negative resistance. OBSOLETE -- Once used for oscillators & amplifiers at microwave frequencies.

Diodes Varactor Diodes (VariCap). Operates with reverse bias. Varying voltage varies junction capacitance. Changes width of depletion region. A few picofarads to >100 pF. Used for variable-frequency oscillators & for FM modulators.

Diodes PIN Diodes. 3rd layer of undoped (intrinsic) material. Forward resistance varies with forward bias voltage. More voltage  lower resistance. Used for RF attenuation & switching.

E6A03 -- Why does a PN-junction diode not conduct current when reverse biased?
Only P-type semiconductor material can conduct current Only N-type semiconductor material can conduct current Holes in P-type material and electrons in the N-type material are separated by the applied voltage, widening the depletion region Excess holes in P-type material combine with the electrons in N-type material, converting the entire diode into an insulator

E6B01 -- What is the most useful characteristic of a Zener diode?
A constant current drop under conditions of varying voltage A constant voltage drop under conditions of varying current A negative resistance region An internal capacitance that varies with the applied voltage

E6B02 -- What is an important characteristic of a Schottky diode as compared to an ordinary silicon diode when used as a power supply rectifier? Much higher reverse voltage breakdown Controlled reverse avalanche voltage Enhanced carrier retention time Less forward voltage drop

E6B03 -- What special type of diode is capable of both amplification and oscillation?
Point contact Zener Tunnel Junction

E6B04 -- What type of semiconductor device is designed for use as a voltage-controlled capacitor?
Varactor diode Tunnel diode Silicon-controlled rectifier Zener diode

E6B05 -- What characteristic of a PIN diode makes it useful as an RF switch or attenuator?
Extremely high reverse breakdown voltage Ability to dissipate large amounts of power Reverse bias controls its forward voltage drop A large region of intrinsic material

E6B06 -- Which of the following is a common use of a hot-carrier diode?
As balanced mixers in FM generation As a variable capacitance in an automatic frequency control circuit As a constant voltage reference in a power supply As a VHF / UHF mixer or detector

E6B07 -- What is the failure mechanism when a junction diode fails due to excessive current?
Excessive inverse voltage Excessive junction temperature Insufficient forward voltage Charge carrier depletion

E6B08 -- Which of the following describes a type of semiconductor diode?
Metal-semiconductor junction Electrolytic rectifier CMOS-field effect Thermionic emission diode

E6B09 -- What is a common use for point contact diodes?
As a constant current source As a constant voltage source As an RF detector As a high voltage rectifier

E6B11 -- What is used to control the attenuation of RF signals by a PIN diode?
Forward DC bias current A sub-harmonic pump signal Reverse voltage larger than the RF signal Capacitance of an RF coupling capacitor

E6B12 -- What is one common use for PIN diodes?
As a constant current source As a constant voltage source As an RF switch As a high voltage rectifier

Bipolar Junction Transistors 3 doped layers. N-P-N. P-N-P. 3 terminals. Collector. Base. Emitter.

Bipolar Transistors Base region very thin. Base-emitter junction is forward biased. Collector-base junction is reverse biased. A small current flowing through base-emitter junction causes a large current to flow through the collector-base junction. Low input impedance. Low output impedance.

Bipolar Transistors Transistor characteristics. Current gain (β). β = IC/IB Alpha (α). α = IC/IE

Bipolar Transistors Transistor characteristics. Alpha Cut-off Frequency. Frequency at which current gain drops to times the value at 1 kHz. Practical upper frequency limit for common-base amplifier. Beta Cut-off Frequency. Practical upper frequency limit for common-emitter amplifier.

Bipolar Transistors Transistor characteristics. Saturation – A bi-polar transistor is said to be “saturated” when an additional increase in base current does not result in an additional increase in collector current. Cut-off – A bi-polar transistor is said to be “cut off” if there is insufficient base current to allow any collector current to flow.

E6A05 -- What is the alpha of a bipolar junction transistor?
The change of collector current with respect to base current The change of base current with respect to collector current The change of collector current with respect to emitter current The change of collector current with respect to gate current

E6A06 -- What is the beta of a bipolar junction transistor?
The frequency at which the current gain is reduced to 1 The change in collector current with respect to base current The breakdown voltage of the base to collector junction The switching speed of the transistor

E6A07 -- Which of the following indicates that a silicon NPN junction transistor is biased on?
Base-to-emitter resistance of approximately 6 to 7 ohms Base-to-emitter resistance of approximately 0.6 to 0.7 ohms Base-to-emitter voltage of approximately 6 to 7 volts Base-to-emitter voltage of approximately 0.6 to 0.7 volts

E6A08 -- What term indicates the frequency at which the grounded-base current gain of a transistor has decreased to 0.7 of the gain obtainable at 1 kHz? Corner frequency Alpha rejection frequency Beta cutoff frequency Alpha cutoff frequency

Field-Effect Transistors (FET) Gate voltage controls channel current. Gain measured in transconductance. G = ID / VG Siemens High input impedance.

Field-Effect Transistors Junction Field-Effect Transistor (JFET).

Field-Effect Transistors Junction Field-Effect Transistor (JFET). A reverse-biased voltage between the gate & source controls the source-drain current. Gate terminal is always reverse-biased. Very little gate current flow. High input impedance. Low output impedance.

Field-Effect Transistors Metal Oxide Semiconductor Field-Effect Transistor (MOSFET).

Field-Effect Transistors Metal Oxide Semiconductor Field-Effect Transistor (MOSFET). Gate is insulated from the source-drain channel. No gate current flow. Very high input impedance. ≥10 megohms. Low output impedance. Susceptible to damage from static discharge. Often have internal Zener diodes to protect gate.

Field-Effect Transistors Metal Oxide Semiconductor Field-Effect Transistor (MOSFET) Depletion Mode Enhancement Mode Dual-Gate

Field-Effect Transistors Enhancement and depletion mode FET’s. Enhancement mode. VG = 0 VDC  No source-drain current flow. Increasing gate voltage  larger source-drain current. Depletion mode. VG = 0 VDC  Non-zero source-drain current flow. Increasing gate voltage  smaller source-drain current.

E6A09 -- What is a depletion-mode FET?
An FET that exhibits a current flow between source and drain when no gate voltage is applied An FET that has no current flow between source and drain when no gate voltage is applied Any FET without a channel Any FET for which holes are the majority carriers

E6A10 -- In Figure E6-2, what is the schematic symbol for an N-channel dual-gate MOSFET?
4 5 6

E6A11 -- In Figure E6-2, what is the schematic symbol for a P-channel junction FET?
3 6

E6A12 -- Why do many MOSFET devices have internally connected Zener diodes on the gates?
To provide a voltage reference for the correct amount of reverse-bias gate voltage To protect the substrate from excessive voltages To keep the gate voltage within specifications and prevent the device from overheating To reduce the chance of the gate insulation being punctured by static discharges or excessive voltages

E6A14 -- How does DC input impedance at the gate of a field-effect transistor compare with the DC input impedance of a bipolar transistor? They are both low impedance An FET has low input impedance; a bipolar transistor has high input impedance An FET has high input impedance; a bipolar transistor has low input impedance They are both high impedance

E6A17 -- What are the names of the three terminals of a field-effect transistor?
Gate 1, gate 2, drain Emitter, base, collector Emitter, base 1, base 2 Gate, drain, source

RF Integrated Devices Monolithic microwave integrated circuit (MMIC). VHF, UHF, microwaves. Typically 50Ω Low Noise Figure Typically 2.0 dB Gallium Arsenide. Gallium Nitride. Highest frequency.

RF Integrated Devices Microstrip Construction. Double-sided PCB. One side is ground plane. Precisely-sized traces form 50Ω transmission line.

E5D03 -- What is microstrip?
Lightweight transmission line made of common zip cord Miniature coax used for low power applications Short lengths of coax mounted on printed circuit boards to minimize time delay between microwave circuits Precision printed circuit conductors above a ground plane that provide constant impedance interconnects at microwave frequencies

E6A01 -- In what application is gallium arsenide used as a semiconductor material in preference to germanium or silicon? In high-current rectifier circuits In high-power audio circuits In microwave circuits In very low frequency RF circuits

E6E03 -- Which of the following materials is likely to provide the highest frequency of operation when used in MMICs? Silicon Silicon nitride Silicon dioxide Gallium nitride

E6E04 -- What is the most common input and output impedance of circuits that use MMICs?
50 ohms 300 ohms 450 ohms 10 ohms

E6E06 -- What characteristics of the MMIC make it a popular choice for VHF through microwave circuits? The ability to retrieve information from a single signal even in the presence of other strong signals. Plate current that is controlled by a control grid Nearly infinite gain, very high input impedance, and very low output impedance Controlled gain, low noise figure, and constant input and output impedance over the specified frequency range

E6E07 -- Which of the following is typically used to construct a MMIC-based microwave amplifier?
Ground-plane construction Microstrip construction Point-to-point construction Wave-soldering construction

E6E08 -- How is voltage from a power supply normally furnished to the most common type of monolithic microwave integrated circuit (MMIC)? Through a resistor and/or RF choke connected to the amplifier output lead MMICs require no operating bias Through a capacitor and RF choke connected to the amplifier input lead Directly to the bias-voltage (VCC IN) lead

Display Devices Light-Emitting Diodes (LED)

Display Devices Light-Emitting Diodes (LED)
Emit light when forward-biased. Forward voltage drop varies with color (material). Red – 1.6 Volts Yellow – 2.0 Volts Green – 4.0 Volts Typically 10 mA to 20 mA for full brightness.

Display Devices Light-Emitting Diodes (LED) Red, green, & yellow.
Gallium-Arsenide, Gallium-Phosphide, or both. Blue. Silicon-Carbide or Zinc-Selenide White. Actually blue LED with yellow phosphor coating on lens.

E6B10 -- In Figure E6-3, what is the schematic symbol for a light-emitting diode?
5 6 7

E6B13 -- What type of bias is required for an LED to emit light?
Reverse bias Forward bias Zero bias Inductive bias

Display Devices Liquid-Crystal Displays
Rotates polarization of light passing through it. Applying voltage across crystal changes polarization.

Display Devices Liquid-Crystal Displays Advantages Disadvantages
Very low power required. Low operating voltage. Thin. Disadvantages Low temperatures affect speed of polarization shift. May be damaged by high temperatures. May be difficult to read in bright light or at an angle.

E6D05 -- What is a liquid-crystal display (LCD)?
A modern replacement for a quartz crystal oscillator which displays its fundamental frequency A display using a crystalline liquid which, in conjunction with polarizing filters, becomes opaque when voltage is applied A frequency-determining unit for a transmitter or receiver A display that uses a glowing liquid to remain brightly lit in dim light

E6D15 -- Which of the following is true of LCD displays?
They are hard to view in high ambient light conditions They may be hard view through polarized lenses They only display alphanumeric symbols All of these choices are correct

Display Devices Charge-Coupled Devices
Combines digital & analog signal processing. Array of capacitors with MOSFET switches on input & output. Basis of nearly all modern cameras, both still & video.

Display Devices Charge-Coupled Devices
Series of “buckets” containing an analog voltage. Analog values transferred from “bucket” to “bucket” when a clock pulse is received.

Digital Logic Logic Basics Combinational logic.
Output state determined by combination of input states. Boolean Algebra. Variables have only 2 values. 0 or 1. False or True. Off or On. Can use a “truth table” to show resulting outputs with all possible combinations of inputs.

Digital Logic Logic Basics One-input elements. Non-inverting buffer.
Inverting buffer or “Not” gate. A B 1 A B 1

Digital Logic Logic Basics AND/NAND gate.
Output true only if ALL inputs are true. A B C 1 A B C 1

Digital Logic Logic Basics OR/NOR gate.
Output true if one or more of the inputs are true. A B C 1 A B C 1

Digital Logic Logic Basics Exclusive (XOR/NXOR) gate.
Output true if one and ONLY one of the inputs is true. A B C 1 A B C 1

Digital Logic Logic Basics Positive & negative logic. Positive logic.
True represented by highest voltage. Negative logic. True represented by lowest voltage. Positive logic NAND functionally equivalent to negative logic NOR (same truth table).

Digital Logic Tri-State Logic
Allows multiple devices to be connected in parallel on same output bus. Input Output Enable or Select

Digital Logic Logic Basics Tri-state logic. Three output states.
Low (0). High (1). Off (high impedance). Allows multiple devices to be connected in parallel on same output bus. Only one device can be “on” at a time. All others MUST be in the high-impedance state.

E6C03 -- What is tri-state logic?
Logic devices with 0, 1, and high impedance output states Logic devices that utilize ternary math Low power logic devices designed to operate at 3 volts Proprietary logic devices manufactured by Tri-State Devices

E6C04 – What is the primary advantage of tri-state logic?
Low power consumption Ability to connect many device outputs to a common bus High speed operation More efficient arithmetic operations

E6C08 -- In Figure E6-5, what is the schematic symbol for a NAND gate?
1 2 3 4

E6C10 -- In Figure E6-5, what is the schematic symbol for a NOR gate?
2 3 4

E6C11 -- In Figure E6-5, what is the schematic symbol for the NOT operation (inverter)?
2 4 5 6

E7A07 -- What logical operation does a NAND gate perform?
It produces a logic "0" at its output only when all inputs are logic "0“ It produces a logic "1" at its output only when all inputs are logic "1“ It produces a logic "0" at its output if some but not all of its inputs are logic "1“ It produces a logic "0" at its output only when all inputs are logic "1“

E7A08 -- What logical operation does an OR gate perform?
It produces a logic "1" at its output if any or all inputs are logic "1“ It produces a logic "0" at its output if all inputs are logic "1“ It only produces a logic "0" at its output when all inputs are logic "1“ It produces a logic "1" at its output if all inputs are logic "0”

E7A09 -- What logical operation is performed by an exclusive NOR gate?
It produces a logic "0" at its output only if all inputs are logic "0“ It produces a logic "1" at its output only if all inputs are logic "1“ It produces a logic "0" at its output if any single input is a logic “1” It produces a logic "1" at its output if any single input is a logic “1”

E7A10 -- What is a truth table?
A table of logic symbols that indicate the high logic states of an op-amp A diagram showing logic states when the digital device's output is true A list of inputs and corresponding outputs for a digital device A table of logic symbols that indicates the low logic states of an op-amp

E7A11 -- What is the name for logic which represents a logic "1" as a high voltage?
Reverse Logic Assertive Logic Negative logic Positive Logic

E7A12 -- What is the name for logic which represents a logic "0" as a high voltage?
Reverse Logic Assertive Logic Negative logic Positive Logic

Digital Logic Synchronous Logic Sequential logic
Current state dependent on both current inputs and previous output state. Must include some form of “memory”.

Digital Logic Synchronous Logic Flip-flops.
a.k.a -- Bi-stable multivibrator, latch. 2 stable states. Several different types. S-R, J-K, D, T. Gated, non-gated. Clocked, non-clocked. Can be used as frequency divider. Each flip-flop divides by 2.

Digital Logic Synchronous Logic
Synchronous and asynchronous flip-flops. Synchronous flip-flops. Clock input. Changes state ONLY at time determined by clock input. Asynchronous flip-flops. No clock input. Changes state whenever any input changes state.

Digital Logic Synchronous Logic Dynamic versus static inputs.
Dynamic inputs. a.k.a. – Edge-triggered. Flip-flop acts ONLY when clock input changes state. Positive-edge triggered. Negative-edge triggered. Static inputs. a.k.a. – Level-triggered. Flip-flop acts when any input changes state.

Digital Logic Synchronous Logic Set-Reset (SR) Latch
Most basic latch type. S R Action No change 1 Q = 0 Q = 1 Forbidden

Digital Logic Synchronous Logic J-K flip-flop
Adds toggle function to SR latch. Must be clocked. Clock (>) J K Action -- No change 1 Q = 0 Q = 1 Toggle (Q = not Q)

Digital Logic Synchronous Logic Monostable multivibrator (One-shot)
Generates one pulse with each trigger. Pulse length determined by R-C time constant. Astable multivibrator (Oscillator) Generates series of pulses. Pulse length & time between pulses determined by R-C time constants.

Digital Logic Synchronous Logic 555 Timer I.C.
One of the most popular IC’s ever made. 1 billion/year. Monostable or astable multivibrator. First introduced 1971 Both bipolar & CMOS versions available

Digital Logic Synchronous Logic 555 Monostable multivibrator
T = 1.1 x R x C

Digital Logic Synchronous Logic 555 Astable multivibrator f =
Ratio of R1 to R2 sets duty cycle. 1.46 C1 x (R1 + (2 x R2))

Digital Logic Frequency Dividers and Counters Divide-by-N counter.
A series of flip-flops connected so that one output pulse occurs after every N input pulses. Each flip-flop divides by 2. Most counters provide an input to clear count. Counters can either count up or down. A decade counter divides by 10. A 4-stage counter (divide by 16) with feedback to reset after 10 input pulses.

Digital Logic Synchronous Logic Frequency divider. Cascaded J-K
flip-flops.

Digital Logic Frequency Dividers and Counters
Asynchronous (ripple) counter. Each input pulse triggers the following stage, so the count “ripples” along the chain.

Digital Logic Frequency Dividers and Counters Synchronous counter.
Each stage in counter triggered by common clock, so each stage in counter changes state at the same time.

E7A01 -- Which of the following is a bi-stable circuit?
An "AND" gate An "OR" gate A flip-flop A clock

E7A02 -- What is the function of a decade counter digital IC?
It produces one output pulse for every ten input pulses It decodes a decimal number for display on a seven segment LED display It produces ten output pulses for every input pulse It adds two decimal numbers together

E7A03 -- Which of the following can divide the frequency of a pulse train by 2?
An XOR gate A flip-flop An OR gate A multiplexer

E7A04 -- How many flip-flops are required to divide a signal frequency by 4?
1 2 4 8

Monostable multivibrator J-K flip-flop T flip-flop
E7A05 -- Which of the following is a circuit that continuously alternates between two states without an external clock? Monostable multivibrator J-K flip-flop T flip-flop Astable multivibrator

E7A06 -- What is a characteristic of a monostable multivibrator?
It switches momentarily to the opposite binary state and then returns to its original state after a set time It produces a continuous square wave oscillating between 1 and 0 It stores one bit of data in either a 0 or 1 state It maintains a constant output voltage, regardless of variations in the input voltage

Digital Logic Logic Families
Several different technologies can be used to build digital circuits. Vacuum tube. RTL ECL TTL CMOS BiCMOS Tri-State Logic

Digital Logic Logic Families (Ancient History) Vacuum tube.

Digital Logic Logic Families (Ancient History)
Resistor-Transistor-Logic (RTL)

Digital Logic Logic Families Transistor-Transistor-Logic (TTL)
+5VDC supply voltage. High level: >2.0 VDC Low level: < 0.8 VDC Threshold: ~0.7 VDC

Digital Logic Logic Families Transistor-Transistor-Logic (TTL)
Open inputs assume a high logic state. Best practice is to use pull-up or pull-down resistors on unused inputs. Resistor tied to +5V to force a high voltage input state. Resistor tied to 0V to force a low voltage input state.

Digital Logic Logic Families
Complementary Metal-Oxide Semiconductor (CMOS) 3-18 VDC supply voltage. High level: Vdd – 0.1 V. Low level: Vss V. Threshold: ~ ½ supply voltage. High noise immunity. Sensitive to static damage. Low power consumption. Current pulse during switchover.

Digital Logic BiCMOS Logic
High input impedance of CMOS. Static-sensitive. Low output impedance of bipolar. Higher power consumption. Complex manufacturing process. More expensive. BiCMOS Logic Combines Bipolar & CMOS devices on same chip. Vout Vdd Vin T2 T4 T1 T3 CL

Digital Logic Programmable Logic Programmable Logic Device (PLD).
A programmable collection of logic gates and circuits in a single integrated circuit. Programmable Gate Array (PGA). Complex logic functions can be created in a single integrated circuit. Field-Programmable Gate Array (FPGA). Device can be programmed by the customer & not just by the manufacturer.

E6A13 -- What do the initials CMOS stand for?
Common Mode Oscillating System Complementary Mica-Oxide Silicon Complementary Metal-Oxide Semiconductor Common Mode Organic Silicon

E6C05 -- Which of the following is an advantage of CMOS logic devices over TTL devices?
Differential output capability Lower distortion Immune to damage from static discharge Lower power consumption

E6C06 -- Why do CMOS digital integrated circuits have high immunity to noise on the input signal or power supply? Larger bypass capacitors are used in CMOS circuit design The input switching threshold is about two times the power supply voltage The input switching threshold is about one-half the power supply voltage Input signals are stronger

E6C07 -- What best describes a pull-up or pull-down resistor?
A resistor in a keying circuit used to reduce key clicks A resistor connected to the positive or negative supply line used to establish a voltage when an input or output is an open circuit A resistor that insures that an oscillator frequency does not drive lower over time A resistor connected to an op-amp output that only functions when the logic output is false

E6C09 -- What is a Programmable Logic Device (PLD)?
A device to control industrial equipment A programmable collection of logic gates and circuits in a single integrated circuit Programmable equipment used for testing digital logic integrated circuits An algorithm for simulating logic functions during circuit design

E6C12 -- What is BiCMOS logic?
A logic device with two CMOS circuits per package An FET logic family based on bimetallic semiconductors A logic family based on bismuth CMOS devices An integrated circuit logic family using both bipolar and CMOS transistors

E6C13 -- Which of the following is an advantage of BiCMOS logic?
Its simplicity results in much less expensive devices than standard CMOS It is totally immune to electrostatic damage It has the high input impedance of CMOS and the low output impedance of bipolar transistors All of these choices are correct

E6C14 -- What is the primary advantage of using a Programmable Gate Array (PGA) in a logic circuit?
Many similar gates are less expensive than a mixture of gate types Complex logic functions can be created in a single integrated circuit A PGA contains its own internal power supply All of these choices are correct

Optoelectronics Photoconductivity Photoelectric effect.
Light striking photosensitive material knocks electrons loose, thereby increasing its conductivity (lower resistance). Most pronounced for crystalline semiconductors. Cadmium-Sulfide: Visible light. Lead-Sulfide: Infra-red light. ALL semiconductor junctions exhibit photoelectric effect.

E6F01 -- What is photoconductivity?
The conversion of photon energy to electromotive energy The increased conductivity of an illuminated semiconductor The conversion of electromotive energy to photon energy The decreased conductivity of an illuminated semiconductor

E6F02 -- What happens to the conductivity of a photoconductive material when light shines on it?
It increases It decreases It stays the same It becomes unstable

E6F06 -- Which of these materials is affected the most by photoconductivity?
A crystalline semiconductor An ordinary metal A heavy metal A liquid semiconductor

Optoelectronics Optoelectronic Components
Most semiconductor devices are enclosed in a metal or plastic package to prevent the photoelectric effect from ambient light to affect the operation of the device. Optoelectronic semiconductors have a transparent case or window in the case to allow ambient light to reach the junction & alter the operation of the device.

Optoelectronics Optoelectronic Components Phototransistor.
A transistor in a clear package to allow light to hit the junction. Transistor turns on when exposed to light. External base connection may or may not be provided.

Optoelectronics Optoelectronic Components Optoisolator or optocoupler.
LED & phototransistor in same package Very high impedance between light source & phototransistor. High degree of isolation between control circuit & power circuit. Functions as a solid-state relay.

Current transfer ratio (CTR) Ratio of output current to input current. Can use a darlington phototransistor to increase CTR.

Sometimes a separate LED & phototransistor separated by a small gap are used. This allows the detection of the presence or absence of an object..

Optoelectronics Optoelectronic Components Optical shaft encoder.
Used for VFO knobs & other controls in many modern rigs. Using 2 detectors allows speed of rotation to be detected.

E6F03 -- What is the most common configuration of an optoisolator or optocoupler?
A lens and a photomultiplier A frequency modulated helium-neon laser An amplitude modulated helium-neon laser An LED and a phototransistor

E6F05 -- Which of the following describes an optical shaft encoder?
A device which detects rotation of a control by interrupting a light source with a patterned wheel A device which measures the strength a beam of light using analog to digital conversion A digital encryption device often used to encrypt spacecraft control signals A device for generating RTTY signals by means of a rotating light source.

E6F07 -- What is a solid state relay?
A relay using transistors to drive the relay coil A device that uses semiconductor devices to implement the functions of an electromechanical relay A mechanical relay that latches in the on or off state each time it is pulsed A passive delay line

E6F08 -- Why are optoisolators often used in conjunction with solid state circuits when switching 120 VAC? Optoisolators provide a low impedance link between a control circuit and a power circuit Optoisolators provide impedance matching between the control circuit and power circuit Optoisolators provide a very high degree of electrical isolation between a control circuit and the circuit being switched Optoisolators eliminate the effects of reflected light in the control circuit

Optoelectronics Photovoltaic Cells.
Photoelectric effect can be used in reverse to generate power.

Optoelectronics Photovoltaic Cells.
If sufficient light falls on a P-N junction, free electrons in the N-type material will absorb energy & flow across the junction into the P-type material. Most common material is Silicon. Most efficient material is Gallium-Arsenide. Fully-illuminated junction yields about 0.5 VDC. Rapidly becoming commercially viable for power generation.

E6F04 -- What is the photovoltaic effect?
The conversion of voltage to current when exposed to light The conversion of light to electrical energy The conversion of electrical energy to mechanical energy The tendency of a battery to discharge when used outside

E6F09 -- What is the efficiency of a photovoltaic cell?
The output RF power divided by the input DC power The effective payback period The open-circuit voltage divided by the short-circuit current under full illumination The relative fraction of light that is converted to current

E6F10 -- What is the most common type of photovoltaic cell used for electrical power generation?
Selenium Silicon Cadmium Sulfide Copper oxide

E6F11 -- What is the approximate open-circuit voltage produced by a fully-illuminated silicon photovoltaic cell? 0.1 V 0.5 V 1.5 V 12 V

E6F12 -- What absorbs the energy from light falling on a photovoltaic cell?
Protons Photons Electrons Holes

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Chapter 5 Components and Building Blocks

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