2291 + Mcqs in Digital Electronics Page 6 McqOptions

251.	Which logic family is characterized by a multiemitter transistor on the input?
A.	ECL
B.	CMOS
C.	TTL
D.	None of the above
Answer» D. None of the above

Discussion

252.	What is the defining difference between microprocessor/DSP systems and other digital systems?
A.	The digital system follows a programmed sequence of instructions that the designer specified.
B.	The microprocessor follows a programmed sequence of instructions that the designer specified.
C.	The digital system is faster.
D.	The microprocessor/DSP is faster.
Answer» B. The microprocessor follows a programmed sequence of instructions that the designer specified.

Discussion

253.	The final step in the device programming sequence is ________.
A.	compiling
B.	downloading
C.	simulation
D.	synthesis
Answer» C. simulation

Discussion

254.	Most look-up tables in field-programmable gate arrays (FGPAs) use ________ inputs, resulting in ________ possible outputs.
A.	4,16
B.	8,16
C.	4,12
D.	6,12
Answer» B. 8,16

Discussion

255.	The problem of the VOH(min) of a TTL IC being too low to drive a CMOS circuit and meet the CMOS requirement of VIH(min) is usually easily overcome by:
A.	adding a fixed voltage-divider bias resistive network at the output of the TTL device
B.	avoiding this condition and only using TTL to drive TTL
C.	adding an external pull-down resistor to ground
D.	adding an external pull-up resistor to
E.	<i>V<sub>CC</sub></i>
Answer» E. <i>V<sub>CC</sub></i>

Discussion

256.	A look-up table is simply a truth table with all the possible output connections listed with their desired input response.
A.	True
B.	False
Answer» C.

Discussion

257.	Why have PLDs taken over so much of the market?
A.	One PLD does the work of many ICs.
B.	The PLDs are cheaper.
C.	Less power is required.
D.	All of the above
Answer» E.

Discussion

258.	What is the advantage of using low-power Schottky (LS) over standard TTL logic?
A.	more power dissipation
B.	less power dissipation
C.	cost is less
D.	cost is more
Answer» C. cost is less

Discussion

259.	Why are the maximum value of VOL and the minimum value of VOH used to determine the noise margin rather than the typical values for these parameters?
A.	These are worst-case conditions.
B.	These are normal conditions.
C.	These are best-case conditions.
D.	It doesn't matter what values are used.
Answer» B. These are normal conditions.

Discussion

260.	A TTL totem-pole circuit is designed so that the output transistors:
A.	are always on together
B.	provide linear phase splitting
C.	provide voltage regulation
D.	are never on together
Answer» E.

Discussion

261.	The most common TTL series ICs are:
A.	E-MOSFET
B.	7400
C.	quad
D.	AC00
Answer» C. quad

Discussion

262.	What does ECL stand for?
A.	It stands for electron-coupled logic; all of the devices used within the gates are N-type transistors.
B.	It stands for emitter-coupled logic; all of the inputs are coupled into the device through the emitters of the input transistors.
C.	It stands for emitter-coupled logic; all of the emitters of the input transistors are connected together and each transistor functions as an emitter follower.
D.	It stands for energy-coupled logic; the input energy is amplified by the input transistors and allows the device to deliver higher output currents.
Answer» D. It stands for energy-coupled logic; the input energy is amplified by the input transistors and allows the device to deliver higher output currents.

Discussion

263.	Which of the following summarizes the important features of emitter-coupled logic (ECL)?
A.	low noise margin, low output voltage swing, negative voltage operation, fast, and high power consumption
B.	good noise immunity, negative logic, high-frequency capability, low power dissipation, and short propagation time
C.	low propagation time, high-frequency response, low power consumption, and high output voltage swings
D.	poor noise immunity, positive supply voltage operation, good low-frequency operation, and low power
Answer» B. good noise immunity, negative logic, high-frequency capability, low power dissipation, and short propagation time

Discussion

264.	The high input impedance of MOSFETs:
A.	allows faster switching
B.	reduces input current and power dissipation
C.	prevents dense packing
D.	creates low-noise reactions
Answer» C. prevents dense packing

Discussion

265.	Why is a pull-up resistor needed when connecting TTL logic to CMOS logic?
A.	to increase the output LOW voltage
B.	to decrease the output LOW voltage
C.	to increase the output HIGH voltage
D.	to decrease the output HIGH voltage
Answer» D. to decrease the output HIGH voltage

Discussion

266.	The time needed for an output to change from the result of an input change is known as:
A.	noise immunity
B.	fan-out
C.	propagation delay
D.	rise time
Answer» D. rise time

Discussion

267.	The word "interfacing" as applied to digital electronics usually means:
A.	a conditioning circuit connected between a standard TTL NAND gate and a standard TTL OR gate
B.	a circuit connected between the driver and load to condition a signal so that it is compatible with the load
C.	any gate that is a TTL operational amplifier designed to condition signals between NMOS transistors
D.	any TTL circuit that is an input buffer stage
Answer» C. any gate that is a TTL operational amplifier designed to condition signals between NMOS transistors

Discussion

268.	What is unique about TTL devices such as the 74S00?
A.	The gate transistors are silicon (S), and the gates therefore have lower values of leakage current.
B.	The S denotes the fact that a single gate is present in the IC rather than the usual package of 2 6 gates.
C.	The S denotes a slow version of the device, which is a consequence of its higher power rating.
D.	The devices use Schottky transistors and diodes to prevent them from going into saturation; this results in faster turn on and turn off times, which translates into higher frequency operation.
Answer» E.

Discussion

269.	The IEEE/ANSI notation of an internal underlined diamond denotes:
A.	totem-pole outputs.
B.	open-collector outputs.
C.	quadrature amplifiers.
D.	tristate buffers.
Answer» C. quadrature amplifiers.

Discussion

270.	Refer to the figure given below. What type of device is shown and what input levels are required to turn the LED off?
A.	The device is an open-collector AND gate and requires both inputs to be HIGH in order to turn the LED off.
B.	The device is a Schottky AND gate and requires only one low input to turn the LED off.
C.	The device is an open-collector AND gate and requires only one low input to turn the LED off.
D.	The device is a Schottky open-collector AND gate and requires a low on both inputs to turn the LED off.
Answer» B. The device is a Schottky AND gate and requires only one low input to turn the LED off.

Discussion

271.	Generally, the voltage measured at an unused TTL input would typically be measured between:
A.	1.4 to 1.8 V.
B.	0 to 5 V.
C.	0 to 1.8 V.
D.	0.8 to 5 V.
Answer» B. 0 to 5 V.

Discussion

272.	The bipolar TTL logic family that was developed to increase switching speed by preventing transistor saturation is:
A.	emitter-coupled logic (ECL).
B.	current-mode logic (CML).
C.	transistor-transistor logic (TTL).
D.	emitter-coupled logic (ECL) and transistor-transistor logic (TTL).
Answer» E.

Discussion

273.	What type of circuit is shown below and which statement best describes its operation?
A.	It is a two-input CMOS AND gate with open drain.
B.	It is a two-input CMOS buffer with tristate output.
C.	It is a CMOS inverter with tristate output.
D.	It is a hybrid TTL-CMOS inverter with FET totem-pole output.
Answer» D. It is a hybrid TTL-CMOS inverter with FET totem-pole output.

Discussion

274.	The rise time (tr) is the time it takes for a pulse to rise from its ________ point up to its ________ point. The fall time (tf) is the length of time it takes to fall from the ________ to the ________ point.
A.	10%, 90%, 90%, 10%
B.	90%, 10%, 10%, 90%
C.	20%, 80%, 80%, 20%
D.	10%, 70.7%, 70.7%, 10%
Answer» B. 90%, 10%, 10%, 90%

Discussion

275.	Cascade chains are closely associated with ________.
A.	CLBs
B.	SOP functions
C.	logic expansion
D.	all of the above
Answer» E.

Discussion

276.	What is the increase in switching speed between 74LS series TTL and 74HC/HCT (High-Speed CMOS)?
A.	5
B.	10
C.	50
D.	100
Answer» C. 50

Discussion

277.	What must be done to interface CMOS to TTL?
A.	A dropping resistor must be used on the CMOS 12 V supply to reduce it to 5 V for the TTL.
B.	As long as the CMOS supply voltage is 5 V, they can be interfaced; however, the fan-out of the CMOS is limited to two TTL gates.
C.	A 5 V Zener diode must be placed across the inputs of the TTL gates in order to protect them from the higher output voltages of the CMOS gates.
D.	The two series cannot be interfaced without the use of special interface buffers designed for that purpose, such as the open-collector buffers.
Answer» C. A 5 V Zener diode must be placed across the inputs of the TTL gates in order to protect them from the higher output voltages of the CMOS gates.

Discussion

278.	What is the static charge that can be stored by your body as you walk across a carpet?
A.	300 volts
B.	3,000 volts
C.	30,000 volts
D.	Over 30,000 volts
Answer» E.

Discussion

279.	The simplest equation which implements the K-map shown below is:
A.	<img src="/_files/images/digital-electronics/digital-systems/mca4_1016a1.jpeg">
B.	<img src="/_files/images/digital-electronics/digital-systems/mca4_1016b1.jpeg">
C.	<img src="/_files/images/digital-electronics/digital-systems/mca4_1016c1.jpeg">
D.	<img src="/_files/images/digital-electronics/digital-systems/mca4_1016d1.jpeg">
Answer» B. <img src="/_files/images/digital-electronics/digital-systems/mca4_1016b1.jpeg">

Discussion

280.	What type of circuit is represented in the given figure, and which statement best describes its operation?
A.	It is a tristate inverter. When the ENABLE input is HIGH, the output is effectively an open circuit it is neither LOW nor HIGH.
B.	It is a programmable inverter. It can be programmed to function as either an active LOW or an active HIGH inverter.
C.	It is an active LOW buffer, which can be turned on and off by the ENABLE input.
D.	None of the above.
Answer» B. It is a programmable inverter. It can be programmed to function as either an active LOW or an active HIGH inverter.

Discussion

281.	Which of the following logic families has the highest noise margin?
A.	TTL
B.	LS TTL
C.	CMOS
D.	HCMOS
Answer» E.

Discussion

282.	How many 1-of-16 decoders are required for decoding a 7-bit binary number?
A.	5
B.	6
C.	7
D.	8
Answer» E.

Discussion

283.	Which of the following logic expressions represents the logic diagram shown?
A.	<img src="/_files/images/digital-electronics/digital-systems/mca4_1018a1.jpeg" align="center">
B.	<img src="/_files/images/digital-electronics/digital-systems/mca4_1018b1.jpeg" align="center">
C.	<img src="/_files/images/digital-electronics/digital-systems/mca4_1018c1.jpeg" align="center">
D.	<img src="/_files/images/digital-electronics/digital-systems/mca4_1018d1.jpeg" align="center">
Answer» E.

Discussion

284.	Which of the following summarizes the important features of ECL?
A.	Low noise margin, low output voltage swing, negative voltage operation, fast, and high power consumption
B.	Good noise immunity, negative logic, high frequency capability, low power dissipation, and short propagation time
C.	Slow propagation time, high frequency response, low power consumption, and high output voltage swings
D.	Poor noise immunity, positive supply voltage operation, good low frequency operation, and low power
Answer» B. Good noise immunity, negative logic, high frequency capability, low power dissipation, and short propagation time

Discussion

285.	A 74HC147 priority encoder has ten active-LOW inputs and four active-LOW outputs. What would be the state of the four outputs if inputs 4 and 5 are LOW and all other inputs are HIGH?
A.	<img src="/_files/images/digital-electronics/digital-fundamentals/mca6_0110a.gif">
B.	<img src="/_files/images/digital-electronics/digital-fundamentals/mca6_0110b.gif">
C.	<img src="/_files/images/digital-electronics/digital-fundamentals/mca6_0110c.gif">
D.	<img src="/_files/images/digital-electronics/digital-fundamentals/mca6_0110d.gif">
Answer» B. <img src="/_files/images/digital-electronics/digital-fundamentals/mca6_0110b.gif">

Discussion

286.	A(n) ________ consists of a programmable array of AND gates that connects to a fixed array of OR gates and is usually OTP.
A.	GAL
B.	CPLD
C.	PAL
D.	SPLD
Answer» D. SPLD

Discussion

287.	When did the first PLD appear?
A.	More than 10 years ago
B.	More than 20 years ago
C.	More than 30 years ago
D.	More than 40 years ago
Answer» D. More than 40 years ago

Discussion

288.	SPLDs, CPLDs, and FPGAs are all which type of device?
A.	PAL
B.	PLD
C.	EPROM
D.	SRAM
Answer» C. EPROM

Discussion

289.	Which of the figures in figure (a to d) is equivalent to figure (e)?
A.	a
B.	b
C.	c
D.	d
Answer» C. c

Discussion

290.	Convert BCD 0001 0111 to binary.
A.	10101
B.	10010
C.	10001
D.	11000
Answer» D. 11000

Discussion

291.	How many data select lines are required for selecting eight inputs?
A.	1
B.	2
C.	3
D.	4
Answer» D. 4

Discussion

292.	Convert BCD 0001 0010 0110 to binary.
A.	1111110
B.	1111101
C.	1111000
D.	1111111
Answer» B. 1111101

Discussion

293.	Which of the following statements accurately represents the two BEST methods of logic circuit simplification?
A.	Boolean algebra and Karnaugh mapping
B.	Karnaugh mapping and circuit waveform analysis
C.	Actual circuit trial and error evaluation and waveform analysis
D.	Boolean algebra and actual circuit trial and error evaluation
Answer» B. Karnaugh mapping and circuit waveform analysis

Discussion

294.	The implementation of simplified sum-of-products expressions may be easily implemented into actual logic circuits using all universal ________ gates with little or no increase in circuit complexity. (Select the response for the blank space that will BEST make the statement true.)
A.	AND/OR
B.	NAND
C.	NOR
D.	OR/AND
Answer» C. NOR

Discussion

295.	Which of the following statements apply to CMOS devices?
A.	The devices should not be inserted into circuits with the power on.
B.	All tools, test equipment, and metal workbenches should be tied to earth ground.
C.	The devices should be stored and shipped in antistatic tubes or conductive foam.
D.	All of the above.
Answer» E.

Discussion

296.	What causes low-power Schottky TTL to use less power than the 74XX series TTL?
A.	The Schottky-clamped transistor
B.	Nothing. The 74XX series uses less power.
C.	A larger value resistor
D.	Using NAND gates
Answer» D. Using NAND gates

Discussion

297.	What are the major differences between the 5400 and 7400 series of ICs?
A.	The 5400 series are military grade and require tighter supply voltages and temperatures.
B.	The 5400 series are military grade and allow for a wider range of supply voltages and temperatures.
C.	The 7400 series are an improvement over the original 5400s.
D.	The 7400 series was originally developed by Texas Instruments. The 5400 series was brought out by National Semiconductors after TI's patents expired, as a second supply source.
Answer» C. The 7400 series are an improvement over the original 5400s.

Discussion

298.	What type of logic circuit is shown below and what logic function is being performed? >
A.	It is an NMOS AND gate.
B.	It is a CMOS AND gate.
C.	It is a CMOS NOR gate.
D.	It is a PMOS NAND gate.
Answer» D. It is a PMOS NAND gate.

Discussion

299.	Which of the logic families listed below allows the highest operating frequency?
A.	74AS
B.	ECL
C.	HCMOS
D.	54S
Answer» C. HCMOS

Discussion

300.	Refer to the given figure. What type of output arrangement is being used for the output?
A.	Complementary-symmetry
B.	Push-pull
C.	Quasi push-pull
D.	Totem-pole
Answer» E.

Discussion

Explore topic-wise MCQs in Engineering.

Which logic family is characterized by a multiemitter transistor on the input?

What is the defining difference between microprocessor/DSP systems and other digital systems?

The final step in the device programming sequence is ________.

Most look-up tables in field-programmable gate arrays (FGPAs) use ________ inputs, resulting in ________ possible outputs.

The problem of the VOH(min) of a TTL IC being too low to drive a CMOS circuit and meet the CMOS requirement of VIH(min) is usually easily overcome by:

A look-up table is simply a truth table with all the possible output connections listed with their desired input response.

Why have PLDs taken over so much of the market?

What is the advantage of using low-power Schottky (LS) over standard TTL logic?

Why are the maximum value of VOL and the minimum value of VOH used to determine the noise margin rather than the typical values for these parameters?

A TTL totem-pole circuit is designed so that the output transistors:

The most common TTL series ICs are:

What does ECL stand for?

Which of the following summarizes the important features of emitter-coupled logic (ECL)?

The high input impedance of MOSFETs:

Why is a pull-up resistor needed when connecting TTL logic to CMOS logic?

The time needed for an output to change from the result of an input change is known as:

The word "interfacing" as applied to digital electronics usually means:

What is unique about TTL devices such as the 74S00?

The IEEE/ANSI notation of an internal underlined diamond denotes:

Refer to the figure given below. What type of device is shown and what input levels are required to turn the LED off?

Generally, the voltage measured at an unused TTL input would typically be measured between:

The bipolar TTL logic family that was developed to increase switching speed by preventing transistor saturation is:

What type of circuit is shown below and which statement best describes its operation?

The rise time (tr) is the time it takes for a pulse to rise from its ________ point up to its ________ point. The fall time (tf) is the length of time it takes to fall from the ________ to the ________ point.

Cascade chains are closely associated with ________.

What is the increase in switching speed between 74LS series TTL and 74HC/HCT (High-Speed CMOS)?

What must be done to interface CMOS to TTL?

What is the static charge that can be stored by your body as you walk across a carpet?

The simplest equation which implements the K-map shown below is:

What type of circuit is represented in the given figure, and which statement best describes its operation?

Which of the following logic families has the highest noise margin?

How many 1-of-16 decoders are required for decoding a 7-bit binary number?

Which of the following logic expressions represents the logic diagram shown?

Which of the following summarizes the important features of ECL?

A 74HC147 priority encoder has ten active-LOW inputs and four active-LOW outputs. What would be the state of the four outputs if inputs 4 and 5 are LOW and all other inputs are HIGH?

A(n) ________ consists of a programmable array of AND gates that connects to a fixed array of OR gates and is usually OTP.

When did the first PLD appear?

SPLDs, CPLDs, and FPGAs are all which type of device?

Which of the figures in figure (a to d) is equivalent to figure (e)?

Convert BCD 0001 0111 to binary.

How many data select lines are required for selecting eight inputs?

Convert BCD 0001 0010 0110 to binary.

Which of the following statements accurately represents the two BEST methods of logic circuit simplification?

The implementation of simplified sum-of-products expressions may be easily implemented into actual logic circuits using all universal ________ gates with little or no increase in circuit complexity. (Select the response for the blank space that will BEST make the statement true.)

Which of the following statements apply to CMOS devices?

What causes low-power Schottky TTL to use less power than the 74XX series TTL?

What are the major differences between the 5400 and 7400 series of ICs?

What type of logic circuit is shown below and what logic function is being performed? &gt;

Which of the logic families listed below allows the highest operating frequency?

Refer to the given figure. What type of output arrangement is being used for the output?

Most look-up tables in field-programmable gate arrays (FGPAs) use inputs, resulting in possible outputs.

The rise time (tr) is the time it takes for a pulse to rise from its point up to its point. The fall time (tf) is the length of time it takes to fall from the to the point.

What type of logic circuit is shown below and what logic function is being performed? >