CHAPTER 14 SPECIAL PURPOSE OP-AMP CIRCUITS

CHAPTER 14
SPECIAL PURPOSE OP-AMP CIRCUITS

1. Provides dc isolation between input and output
Isolation amplifier

2. Ratio of the output current to the input voltage
Transconductance

3. Transconductance is __________ of an OTA
Gain

4. A comparator with hysteresis where the input voltage is large enough to drive the device into its saturated states
Schmitt trigger

5. The ______________ of a number is the power to which the base must be raised to get that number.
Logarithm

6. An amplifier that produces an output that is proportional to the logarithm of the input.
Log amplifier

7. Used in applications where it is necessary to have an output current that is controlled by an input voltage.
Voltage-to-current converter

8. The circuit used to detect the peak of the input voltage and store that peak voltage on a capacitor.
Peak detector

9. The exponent to which the base e must be raised in order to equal a given quantity.
Natural logarithm

10. In an OTA, transconductance varies with _________.
Bias current

11. Amplifiers that are often used in HF communication systems, including fiber optics, for processing wide dynamic range signals.
Log and antilog amplifiers

12. The key characterisctic of an instrumentation amplifier
CMRR

13. The voltage gain of instrumentation amplifier is set by a
Resistor

14. The log amplifier may use the ___________ junction of a BJT in the feedback loop
Base-emitter

15. The main purpose of an instrumentation amplifier is to amplify _____ signals that are riding on _____ common-mode voltages.
small, large

16. The ___________ of an OTA is the input voltage times the transconductance
Output current

17. The operation of log and antilog amplifiers is based on the __________ characteristics of a pn junction
Nonlinear
(logarithmic)

18. A log amplifier has a pn junction in the feedback loop, and an antilog amplifier has a pn junction in __________ with the input
Series

19. In a peak detector, an op-amp is used as a __________ to charge a capacitor through a diode to the peak value of the input voltage.
Comparator

20. A basic instrumentation amplifier is formed by three op-amps and ________ resistors, including the gain setting resistor.
Seven (7)

21. An oscillator that can be either amplitude or pulse modulated by the signal from the input amplifier
High-frequency oscillator

CHAPTER 13 BASIC OP-AMP CIRCUITS

CHAPTER 13
BASIC OP-AMP CIRCUITS

1. A common interfacing process often used when a linear analog system must provide inputs to a digital system.
A/D conversion

2. Method of A/D conversion that uses parallel comparators to compare the linear input signal with various reference voltages developed by a voltage divider
Flash

3. Produces an output that is proportional to the rate of change of the input voltage
Differentiator

4. The difference between the UTP and the LTP
Hysteresis voltage

5. Used to generate pulse waveform from the sine wave output of the audio generator.
Voltage comparator

6. When the output is at the maximum positive voltage and the input exceeds UTP, the output switches to the _________ negative voltage
Maximum

7. Uses a capacitor in the feedback path which is open to dc. This implies that the gain at dc is the open-loop gain of the op-amp.
Practical integrator

8. Gives an op-amp noise immunity
Hysteresis

9. Used to detect positive and negative voltages by connecting a fixed reference voltage source to the inverting input of a zero-level detector.
Nonzero-Level detection

10. A good example of hysteresis
Thermostat

11. A comparator with three trigger points
Schmitt Trigger

12. The output of Schmitt trigger is
Pulse waveform

13. In a comparator with output bounding, what type of diode is used in the feedback loop?
Zener

14. Necessary components for the design of a bounded comparator
Rectifier and zener diodes

15. Type of circuit that uses comparators
Nonzero-level detector

16. Variations of the basic summing amplifier
Averaging and scaling amplifier

17. Differentiation of a ramp input produces a step output with an amplitude proportional to the _________
Slope

18. Another term for flash
Simultaneous

19. Integration of a step input produces a ramp output with the slope proportional to the _________
Amplitude

CHAPTER 12 THE OPERATIONAL AMPLIFIER

CHAPTER 12
THE OPERATIONAL AMPLIFIER

1. The measure of an amplifier’s ability to reject common-mode signals
CMRR

2. It is the typical value of input offset voltage in the ideal case.
0 V

3. It is the dc current required by the inputs of the amplifier to properly operate the first stage.
Input bias current

4. It is the resistance viewed from the output terminal of the op-amp
Output impedance

5. The total resistance between the inverting and noninverting inputs
Differential input impedance

6. Differential impedance is measured by determining the change in ___________ for a given change in differential input voltage.
Bias current

7. Common temperature coefficient for the offset current
0.5nA/°C

8. Functions of negative feedback in an op-amp
Stabilize gain and increase frequency response

9. The voltage gain of an op-amp with external feedback
Closed-loop voltage gain

10. A special case of the noninverting amplifier where all of the output voltage is fed back to the inverting input by a straight connection
Voltage-follower configuration

11. The value of the frequency at which the gain steadily decreases to a point where it is equal to unity
Unity-gain frequency Or unity gain bandwidth

12. It is always equal to the frequency at which the op-amp’s open- loop gain is unity or 0 dB.
Gain-bandwidth product

13. The relative angular displacement of a time-varying function relative to a reference.
Phase shift

14. The three terminals of the basic op-amp not including power and ground
Inverting input, noninverting input, and output

15. It has the highest input impedance and the lowest output impedance of the three amplifier configurations
Voltage-follower

16. The _________ of an op-amp equals the upper critical frequency.
Bandwidth

17. Two types of op-amp input operation.
Differential mode and common-mode

18. A ____________ differentiator uses a capacitor in series with the inverting input.
Ideal
19. An ideal op-amp has ___________ value for voltage gain, bandwidth, and input impedance.
Infinite

20. What should be the output voltage of an op-amp when the differential input is zero
Zero

21. The ideal op-amp has __________ output impedance
Zero

22. The three basic op-amp configurations
Inverting, noninverting, and voltage follower

23. The closed-loop voltage gain is _________ than the open-loop voltage gain. (more or less)
Less

24. Does the gain of an op-amp decreases or increases as frequency increases above the critical frequency
Decreases

25. Devices such as the diode and the transistor which are separate devices that are individually packaged and interconnected in a circuit with other devices to form a complete, functional unit.
Discrete components

26. Most op-amps operate with how many dc supply voltage?
2 (positive and negative)

27. Datasheets often refer to the open-loop voltage gain as the ______________
Large-signal voltage gain

CHAPTER 11 THYRISTORS

CHAPTER 11
THYRISTORS

1. It is like the four-layer diode but with the added gate connection
SCR

2. This is the maximum continuous anode current that the device can withstand in the conduction state under specifies conditions.
Average forward current

3. What bilateral thyristor functions basically like two parallel SCRs turned in opposite directions with a common gate terminal?
Triac

4. ____________ does not belong to the thyristor family because it does not have a four-layer type of construction.
UJT

5. It can be used a trigger device for SCRs and triacs.
UJT

6. It is a type of three-terminal thyristor that is triggered into conduction when the voltage at the anode exceeds the voltage at the gate.
PUT

7. A region of forward bias in which the device has a very high forward resistance and is in the off state
Forward-blocking region

8. A method for turning-off the SCR that basically requires momentarily forcing current through the SCR in the direction opposite to the forward conduction
Forced commutation

9. The value of gate current necessary to switch the SCR from the forward-blocking region to the forward-conduction region under specified conditions.
Gate Trigger Current

10. A four-layer semiconductor device that operates essentially as does the conventional SCR except that it can also be light-triggered.
LASCR

11. Functions basically like two parallel 4- layer diodes turned in opposite directions.
Diac

12. A diac with gate terminal
Triac

13. A four-terminal thyristor that has two gate terminals that are used t trigger the device on and off
Silicon Controlled Device (SCS)

14. A type of three-terminal thyristor that is triggered into conduction when the voltage at the anode exceeds the voltage at the gate.
Programmable Unijunction Transistor (PUT)

15. The characteristic of a UJT that determines its turn-on point
Standoff-ratio

16. The four-layer diode is also called
Shockley diode

17. The region that corresponds to the on condition of the SCR where there is forward current from anode to cathode through the very low resistance of the SCR
Forward_ conduction region

18. The SCR can only be turned on using its _________ terminal
Gate

19. Acts as the trigger source in the LASCRs
Light

20. A thyristor that conducts when the voltage across its terminals exceeds the breakover potential
4-layer diode

21. Basic methods of for turning off an SCR
Anode current interruption and forced commutation

CHAPTER 10 AMPLIFIER FREQUENCY RESPONSE

CHAPTER 10
AMPLIFIER FREQUENCY RESPONSE

1. The frequency at which the output power drops to one-half of its midrange value
Corner frequency

2. At the critical frequencies the output voltage is 70.7% of its midrange value. What is the value of voltage gain in dB?
-3 dB

3. What is the other term for lower critical frequency?
All of the above

4. The condition where the gain is down 3 dB is logically called _________ of the amplifier response
-3 dB point

5. The upper and lower dominant critical frequencies are sometimes called
Half-power frequencies

6. A characteristic of an amplifier in which the product of the voltage gain and the bandwidth is always constant when the roll-off is -20 dB/ decade.
Gain-bandwidth product

7. Critical frequencies are values of frequency at which the RC circuits reduce the voltage gain to ____________ of its midrange value.
70.7%

8. An octave of frequency change is a ________ -times change
2

9. Which of the following has no effect on the low-frequency response?
Internal transistor capacitances

10. What is the gain that occurs for the range of frequencies between the lower and upper critical frequencies?
Midrange gain
11. Which of the following is not a method in frequency response measurement?
Roll-off measurement

12. If the voltage gain is less than one, what is the value of the dB gain?
Negative

13. A plot of dB voltage gain versus frequency on semilog graph paper
Bode plot

14. The critical frequency at which the curve “breaks” into a -20dB/decade drop
Lower break frequency

15. The change in gain or phase shift over a specified range of input signal frequencies
Frequency response

16. A unit of logarithmic gain measurement and is commonly used to express amplifier response
Decibel

17. The lower and upper critical frequencies of an amplifier can be determined using the _____________ method by applying a voltage step to the input of the amplifier and measuring the rise and fall times of the resulting output voltage
Step-response method

18. The coupling an bypass capacitors of an amplifier affect the _________ frequency response: high or low
Low

19. The internal transistor capacitances affect the _________ frequency response: high or low
High

20. Two frequency response measurement
Frequency/amplitude and step

21. The Miller input and output capacitances for a BJT inverting amplifier depends on
Voltage gain

22. When dB is negative, it is usually called_______
Attenuation

CHAPTER 9 FET AMPLIFIERS AND SWITCHING CIRCUITS

CHAPTER 9
FET AMPLIFIERS AND SWITCHING CIRCUITS

1. An amplifier that primarily uses only MOSFETs.
Class D

2. A process in which an input signal is converted to a series of pulses with widths that varies proportionally to the amplitude of the input signal.
PWM

3. It removes the modulating frequency and harmonics and passes only the original signal to the output.
Low-Pass Filter

4. The voltage gain of a common-drain amplifier is always
Slightly less than 1

5. The load resistance connected to the drain of a common-source amplifier reduces ____________
Voltage gain

6. What is the relationship between the input resistance of a common-gate amplifier to its transconductance?
They are inversely proportional

7. The efficiency of a class D amplifier approaches
100%

8. The input signal is applied to the gate and the output is taken from source
Common-drain

9. A nonlinear amplifier in which the transistors are operated as switches
Class D

10. A device that switches an analog signal on and off
Analog switch

11. Consists of two or more analog switches that connect sample portions of their analog input signals to single output in a time sequence
Analog multiplexer

12. Used in low-power digital switching circuits
CMOS

13. Amplifier commonly used as frequency multiplier
Class C

14. The least efficient amplifier
Class A

15. An amplifier that is biased below cutoff
Class c

16. A class of amplifier that operates in the linear region for only a small part of the input cycle
Class C

17. In a class AB amplifier, if the VBE drops are not matched to the diode drops or if the diodes are not in thermal equilibrium with the transistors, this can result in
Thermal runaway

CHAPTER 8 FIELD –EFFECT TRANSISTORS

CHAPTER 8
FIELD –EFFECT TRANSISTORS

1. FETs are preferred device in low-voltage switching applications; while______ transistor is generally used in high-voltage switching applications.
IGBT

2. What type of JFET operates with a reverse-biased pn junction to control current in the channel?
JFET

3. An n-channel universal transfer characteristic curve is also known as
Transconductance curve

4. The change in drain current for a given change in gate-to-source voltage with the drain-to-source voltage constant
Forward transconductance

5. What is the most common type of JFET bias?
Self-bias
6. It is a method for increasing the Q-point stability of a self-biased JFET by making the drain current essentially independent of gate-to-source voltage
Current-source bias

7. What JFET bias uses a BJT as a constant-current source?
Current-source bias

8. For increased Q-point stability, the value of RS in the self-bias circuit is increased and connected to a negative supply voltage. This sometimes called
Dual-supply bias

9. VGS varies quite a bit for JFET self-bias and voltage-divider bias but ID is much more stable with
Voltage-divider bias

10. ____________ is sometimes called depletion/enhancement MOSFET.
D-MOSFET

11. LDMOSFET has a lateral channel structure and is a type of
Enhancement MOSFET

12. It is an example of the conventional E-MOSFET designed to achieve higher power capability
VMOSFET

13. Following are the three ways to bias a MOSFET except
Current-source bias

14. The insulated-gate bipolar transistor combines which two transistors that make it useful in high-voltage and high-current switching applications?
BJT and MOSFET

15. What are the three terminals of IGBT?
Gate, collector, emitter

16. In terms of switching speed, __________ switch fastest and _____________ switch slowest.
MOSFETs, BJTs

17. In a MOSFET, the process of removing or depleting the channel of charge carriers and thus decreasing the channel conductivity
Depletion

18. The ratio of change in drain current to a change in gate-to source voltage in a FET
Transconductance

19. A FET is called a ______________ because of the relationship of the drain current to the square of a term containing gate-to-source voltage
Square-law device
20. Combines features from both the MOSFET and the BJT that make it useful in high-voltage and high-current switching applications.
IGBT

21. Has a lateral channel structure and is a type of enhancement MOSFET designed for power applications.
LDMOSFET

CHAPTER 7 POWER AMPLIFIERS

CHAPTER 7
POWER AMPLIFIERS

1. It is the product of Q-point current and voltage of a transistor with no signal input
Power dissipation

2. The ____________ of an amplifier is the ratio of the output signal power supplied to a load to the total power from the dc supply.
Efficiency

3. Which amplifier operates in the linear region for 180 deg. Of the input cycle when biased in cutoff and is in cutoff for 180 deg?
Class B

4. These amplifiers are biased to conduct for slightly more than 180 deg.
Class AB

5. An amplifier that is generally used in Radio Frequency applications
Class C

6. Implemented with a laser diode
Current mirror

7. An amplifier that is biased below cutoff and is normally operated with resonant circuit load
Class C

8. The four classes of power amplifiers are classified based on the percentage of the ____________which the amplifier operates in its ________region
Input cycle, linear

9. It is the ratio of the output power to the input power
Power gain

10. Product of the rms load current and the rms load voltage
Output power

11. A type of class B amplifier with two transistors in which one transistor conducts for one half-cycle and the other conducts for the other half-cycle
Push-pull

12. Amplifiers that are generally used in Radio Frequency Applications.
Class C amplifiers

13. Another term for complementary Darlington
Sziklai pair

14. An advantage of push-pull class B and class AB amplifiers over class A
Efficiency

15. The Q-point is at _________ at class B operation
Cutoff

16. Operates in the linear region where the output signal is an amplified replica of the input signal
Class A

17. Amplifiers that have the objective of delivering power to a load
Power amplifers

18. When the Q-point is at the center of the ac load line, a maximum class ________ signal can be obtained.
A

19. The maximum efficiency of capacitively coupled class A amplifier cannot be higher than
25%

20. The low efficiency of class A amplifiers limits their usefulness to small power applications that require usually less than ________.
1 W

CHAPTER 6 BJT AMPLIFIERS

CHAPTER 6
BJT AMPLIFIERS

1. Amplifiers designed to handle small __________ signals are referred to as small-signal amplifiers.
ac only

2. Which of the r parameters is the most important?
r’e

3. Determine the ac emitter resistance that is operating with a dc emitter current of 5mA.
5.0 Ω

4. If βac=hfe, αac=?
hfb

5. Which of the three amplifier configurations exhibit high voltage gain and high current gain?
Common-emitter

6. An amplifier configuration which has a voltage gain of approximately 1, a high input resistance and current gain,
Common-collector

7. An amplifier configuration which provides high voltage gain with a maximum current gain of 1.
Common-base

8. Which of the amplifier configurations is the most appropriate for certain applications where sources tend to have low-resistance outputs?
Common-base

9. In a common-emitter amplifier, any change in input signal voltage results in
Opposite change in collector signal voltage

10. The ac voltage gain is the ratio of
ac output voltage at the collector to ac input voltage at the base

11. the reduction in signal voltage as it passes through a circuit
attenuation

12. the overall voltage gain of the common-emitter amplifier is the product of the voltage gain from base to collector and
reciprocal of the attenuation

13. Without the bypass capacitor, the CE amplifier’s emitter is no longer at ac ground. How does this affect the amplifier?
It decreases the ac voltage gain

14. The measure of how well an amplifier maintains its design values over changes in temperature,
Stability

15. Swamping is a method used to minimize the effect of the ____________without reducing the voltage gain to its minimum value.
ac emitter resistance

16. ___________ contains two transistors. The collectors of two transistors are connected and the emitter of the first drives the base of the second.
Darlington pair

17. _____________ consists of two types of transistors, npn and a pnp.
Complementary Darlington

18. An amplifier configuration in which the input signal is capacitively coupled to the emitter and the output is capacitively coupled from the collector,
Common-base

19. Which of the amplifier configurations is/are useful at high frequencies when impedance matching is required?
Common-base

20. The power gain of a common-base amplifier is approximately equal to
Voltage gain

21. BJT amplifier that produces output that are a function of the difference between two input voltages,
Differential amplifier

22. Ideally, a diff-amp provides a very high gain for single-ended or differential signals and _____________ gain for common-mode signals.
0

23. Input signals are out of phase
Differential amplifier

CHAPTER 5  
TRANSISTOR BIAS CIRCUITS

1. What biasing method is common in switching circuits?  
Base bias
 
2. A Base bias in linear region shows that it is  
Directly dependent on dc beta

3. In an emitter-feedback bias, if the collector current increases, the emitter voltage Increases

4. What happens to the base voltage in no. 10?  
Increases
 
5. In an emitter-feedback, the increase in base voltage _________ the base current. Reduces
 
6. For collector-feedback bias, what provides the bias for the base-emitter junction? Collector voltage
 
7. As temperature goes up in a collector-feedback circuit, βDC and VBE goes _______ and __________, respectively.  
Up and down

8. Collector-feedback bias provides good stability using negative feedback from  
Collector to base

9. Innovations in technology would allow a doubling of the number of transistors in a given space every year and that the speed of those transistors would increase. This prediction is widely known as  
Moore’s law

10. If an amplifier is not biased with correct dc voltages on the input and output, it can go ___________ when an input signal is applied.  
Saturation or cutoff

11. Given a voltage-divider biased BJT, determine IC given VCC, R1, R2, RC, and RE which are 10V, 10kohms, 4.7kohms, 1kohm, and 470ohms respectively. Use βDC= 100.  
5.31mA

12. What is the value of VCE in no.20?
2.19 V

13. If an emitter resistor is added to a base bias circuit, what is the value of the emitter current given VCC, RE, RC, and RB as 10V, 1kΩ, 470Ω, and 180kΩ, respectively. Use βDC=100.
3.32mA

14. Calculate for VCE in no. 22
5.12 V

15. If the dc beta in the preceding drops half of its original value, find the percent change in IC.
39.16%

16. What is the percent change in VCE?
27.17%

17. The region along the load line including all points between saturation and cutoff
Linear region

18. A voltage divider for which loading effects can be neglected
Stiff voltage divider

19. The base bias circuit arrangement has poor stability because its Q-point varies widely with
Dc beta

20. The purpose of biasing a circuit is to establish a proper stable ________.
Q-point

21. The process of returning a portion of a circuit’s output back to the input in such a way as to oppose or aid a change in the output
Feedback

TRANSMISSION FUNDAMENTALS (C1 Past Board :excel:)

CHAPTER 1 TRANSMISSION FUNDAMENTALS (Past Board :excel:)

ECE Board Exam April 2001

An SWR reading which has a short circuit termination.

Infinity

ECE Board Exam November 2000

In an open wire transmission line, what is the normal separation between its two (2) conductors?

2 to 6 cm

ECE Board Exam April 2000

Which of the following term is used to describe the attenuation and phase shift per unit length of a transmission line?

Propagation constant

ECE Board Exam November 1999

An indication in radio communication when the voltage standing wave ratio is equal to zero.

No input power

ECE Board Exam April 1999

Refers to a connector that normally connects RG-213 coaxial. cable to an HF transceiver.

PL-259

ECE Board Exam November 1998

Width of frequency band just enough to ensure the transmission of information at a required rate and quality required, and under a specified condition and class of emission.

Necessary bandwidth

ECE Board Exam. April 1998

Best describe a dip meter.

A variable LC oscillator with metered feedback current

ECE Board Exam. April 1997

The standard test tone.

0 dBm

ECE Board April 1997

If voltage change is equal to twice its original value,. what is it corresponding change In dB?

6 dB

ECE Board Exam November 1996

Energy that has neither been-radiated into space,nor completely transmitted.

Standing waves

ECE Board Exam April 1997

To a couple a coaxial line, it is better to use a________

Balun

ECE Board Exam November 2000

What is the main reason,why coaxial cable is not used in microwe signal transmission?

High attenuation

ECE Board Exam April 1997

What is impedance of a balance 4-wire with a diameter of 0.25 spaced 2.5 cm apart using an insulator with a dielectric constant of 2.56?

100 ohms

ECE Board April 2000

In wire communications, non-resonat transmission lines are referred to as __________

Flat lines

ECE Board Exam November 1999

An electronic equipment used in radio communications to measure standing wave ratio.

Reflectometer

ECE Board Exam April 1999

How  does a shorted half-wave line act at a certain operating frequency?

Series resonant circuit

ECE Board Exam November 1998

Best choice of transmission line component to couple a coaxial line to a parallel-wire line.

Balun

ECE Board Exam April 1998

Referred to the dielectric constant of a transmission line material.

Velocity factor

ECE Board Exam April 1997

What is the characteristic impedance of a single wire with a diameter d=0.25 mm placed at the center between grounded parallel planes separated by 1 mm apart? The wire is held by a material with a velocity factor of 0.75?

75 ohms

ECE Board Exam March 1996

The power of standard test tone is normally ______

1mW

ECE Board Exam November 1996

Which tester is used to measure SWR?

Reflectometer

ECE Board Exam March 1996

The characteristic impedance of a transmission line does not depend upon its________

Length

ECE Board Exam April 2000

What is the input impedance equivalent of an open ended transmission line which is longer than a quarter wavelength?

As pure inductor

ECE Board Exam November 1999

In the study of transmission cable, twin lead. is also referred to as a_________

ribbon cable

ECE Board Exam April 1999

The greater the diameter of a wire, the _________ is the resistance.

Lesser

ECE Board Exam November 1998

What determines the velocity factor in transmission line?

Dielectrics in the line

ECE Board Exam April 1998

Technical study which deals with production, transport and delivery of a quality signal from source to destination

Transmission System Engineering

ECE Board Exam April 1997

If you have available number of power amplifiers with a gain of 100 each how many such amplifiers do you need to cascade to give an overall gain of 60 dB?

3 amplifiers

ECE Board Exam March 1996

What :is the reference tone level for dBm?

-90dBm

ECB Board Exam April 2060

What is the term for the ratio of actual velocity at which a signal travels through a line to the speed of light in a vacuum?

Velocity factor

ECE Board Exam November 1999

Referred to as a cause of crosstalk.

Electrical coupling between transmission media

ECE Board Exam November 1998

What is the meaning of the term velocity factor of a transmission line?

The velocity of the wave on the transmission line divided by the velocity of the light in a vacuum

ECE Board Exam April 1998

It is used to connect computers in the same building or in same area.

LAN

ECE Board Exam April 1997

What do you call the energy that was not radiated into space or completely transmitted?

Standing waves

ECE Board Exam November 1996

What is the applied power if a thermal RF wattmeter is connected to a transmitter through  variable attenuator? The wattmeter reads 84 mW when 15 dB of attenuation is used.

2.656 Watts

ECE Board Eaagl.March 1996

If the terminating impedance is exactly equal to the characteristic impedance of the transmission line the return loss is ______

infinite

ECE Board Exam April 1997

A singie.q nductor running from the transmitter to the antenna.

Single line wire

ECE Board Exam November 1996

Ina transmission line if the maximum current to minimum current ratio is 2:1. what is the ratio of the maximum voltage to minimum voltage?

2.1

ECE Board Exam March 1996

What is the main purpose of a communications system?

To provide an acceptable replica of the information at the destination

ECE Board Exam April 1997

__________ sets the limit on the maximum capacity of a channel with a gin noise level.

Shannon-Hartley theorem

ECE Board Exam November 1996

Which stands for dB relative level?

dBr

ECE Board Exam March 1996

To connect coaxial line to a parallel-wire, _______ is the best to use

Balun

ECE Board Exam November 1998

Which of the following determines the characteristics of a transmission line?

Physical dimensions

ECE Board Exam.April 1998

Which of the fotlowing is an impedance matching ratio of coax balun?

4:1

ECE Board Exam November 1997

An electronic equipment used to measure standing wave ratio.

Reflectometer

ECE Board Exam April 1997

What frequency does oxygen cause excessive attenuation?

60 GHz

ECE Board Exam November 1996

The standing wave ratio is equal to _________ if the load is properly matched with the transmission line.

1

ECE Board Exam March 1996

Characteristic impedance of a transmission line is the impedance measured at the ____ when its length is infinite.

Input

ECE Board Exam March 1996

What.quarterwave transformer will match a 100 ohms line to an antenna whose value is 175 ohms?

132.29 ohms

ECE Boardd Exam March 1996

When a transmission line uses ground return, it is called a/an __________ line.

Unbalanced

ECE Board Exam November 1996

Transmission lines when connected to antenna have

resistive load atthe resonant frequency

ECE Board Exam March 1996

Termination means

load connected to the output end of a transmission line

ECE Board Exam March 1996

Transmission lines are either balanced or unbalanced will respect to 

ground

ECE Board Exam March 1996

What is the velocity factor for non-foam dielectric 50 or 75 ohms flexible coaxial cable such as RG 8, 11, 58, and 59?

0.66

Board Exam November 1997

Propagation mode of microwave in a waveguide is known as _____

TE

Board Exam November 1998

A transmission line consisting of two conductors that have equal resistance per unit length.

Balanced line

ECE Board Exam November 1966

What is the equivalent output of a circuit in dBm, if it has an output of 10 Watts?

40 dBm

ECE Board Exam March 1996

Power is always ___________

a definite amount of energy

the rate at which energy is used

expressed in watts

ECE Board Exam November 1998

Which of the following is not a common transmission line impedance?

A.        50 ohms

B.        120 ohms

C.      75 ohms

D.      650 ohms

ECE Board Exam November 1997

The Width of the frequency band which is just sufficient to ensure the transmission of information of information at the rate and with the quality required under a specified condition and class of emission.

Necessary bandwidth

ECE Board Exam November 1996

Transmission line must be matched to the load to

transfer maximum power to the load

ECE Board Exam November 1996

When electromagnetic waves are propagated through a waveguide, they

are reflected from the walls but do not travel along them

ECE Board Exam November 1997

Coaxial lines are used on those system operating

Below 2 GHz

ECE Board Exaru.November 1996

You are measuring a voice channel at a -4 dB test point level, the meter reads 73 dBm (pure test tone) convert the reading into dBrnCO.

21 dBrnCO

ECE Board Exam November 1996

1 micron is equal to ___________ meter(s)

10^-6

ECE Board Exam November 1998

Best reason for pressurizing waveguides with dry air.

To reduce the possibility of internal arcing

ECE Board Exam November 1997

The outer conductor of a coaxial transmission line is always.grounded at the

input and output

ECE Board Exam November 1996

You are measuring noise in a voice channel at 7 dB test point level. The meter reads -56 dBm (FIA weighted). What is the reading in dBrnC?

34 dBrnC

ECE Board Exam November 1998

What do you call the phenomenon in digital circuits that describe the duration of time digital signal passes a circuit?

Propagation delay