MCQOPTIONS
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MCQOPTIONS
This section includes 64 Mcqs, each offering curated multiple-choice questions to sharpen your Digital Electronics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Assume that a particular IC has a supply voltage () equal to +5 V and = 10 mA and = 23 mA. What is the power dissipation for the chip? |
| A. | 50 mW |
| B. | 82.5 mW |
| C. | 115 mW |
| D. | 165 mW |
| Answer» C. 115 mW | |
| 2. |
The problem of the V of a TTL IC being too low to drive a CMOS circuit and meet the CMOS requirement of V 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 |
| Answer» E. | |
| 3. |
Why are the maximum value of and the minimum value of 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. | |
| 4. |
The rise time () is the time it takes for a pulse to rise from its ________ point up to its ________ point. The fall time () 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% | |
| 5. |
The problem of interfacing IC logic families that have different supply voltages ('s) can be solved by using a: |
| A. | level-shifter |
| B. | tristate shifter |
| C. | decoupling capacitor |
| D. | pull-down resistor |
| Answer» B. tristate shifter | |
| 6. |
How is the speed–power product of a logic family determined? |
| A. | The propagation delay in s is multiplied by the power dissipation in mW. |
| B. | The propagation delay in ms is multiplied by the power dissipation in W. |
| C. | The propagation delay in ns is multiplied by the power dissipation in mW. |
| D. | The propagation delay in ns is multiplied by the power dissipation in W. |
| Answer» D. The propagation delay in ns is multiplied by the power dissipation in W. | |
| 7. |
As a general rule, the lower the value of the speed–power product, the better the device because of its: |
| A. | long propagation delay and high power consumption |
| B. | long propagation delay and low power consumption |
| Answer» C. | |
| 8. |
Interfacing (74HCMOS to 74ALSTTl or 74TTL to 74LSTTL) can be done with no danger. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 9. |
Schottky logic overcomes the saturation and stored charge problem by placing a Schottky diode across the base-to-collector junction. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 10. |
PMOS and NMOS are commonly used for small memories and microprocessors. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 11. |
A pulse is not perfectly square; it takes time for the digital level to rise from 0 up to 1 and to fall from 1 down to 0. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 12. |
How can ECL have both a NOR and an OR output? |
| A. | ECL does not have this feature. |
| B. | They are simply the inverse of each other. |
| Answer» C. | |
| 13. |
PMOS and NMOS ________. |
| A. | represent MOSFET devices utilizing either P-channel or N-channel devices exclusively within a given gate |
| B. | are enhancement-type CMOS devices used to produce a series of high-speed logic known as 74HC |
| C. | represent positive and negative MOS-type devices, which can be operated from differential power supplies and are compatible with operational amplifiers |
| D. | None of the above |
| Answer» B. are enhancement-type CMOS devices used to produce a series of high-speed logic known as 74HC | |
| 14. |
In TTL the noise margin is between 0.8 V and 0.4 V. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 15. |
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% | |
| 16. |
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 VCC |
| Answer» E. | |
| 17. |
Using the schematic diagram of a TTL NAND gate, determine the state of each transistor (ON or OFF) when all inputs are high. |
| A. | Q1-ON, Q2-OFF, Q3-ON, Q4-OFF |
| B. | Q1-ON, Q2-ON, Q3-OFF, Q4-OFF |
| C. | Q1-OFF, Q2-OFF, Q3-ON, Q4-ON |
| D. | Q1-OFF, Q2-ON, Q3-OFF, Q4-ON |
| Answer» E. | |
| 18. |
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 | |
| 19. |
As a general rule, the lower the value of the speed–power product, the better the device because of its: |
| A. | long propagation delay and high power consumption |
| B. | long propagation delay and low power consumption |
| Answer» C. | |
| 20. |
When is a level-shifter circuit needed in interfacing logic? |
| A. | A level shifter is always needed. |
| B. | A level shifter is never needed. |
| C. | when the supply voltages are the same |
| D. | when the supply voltages are different |
| Answer» E. | |
| 21. |
What is the range of invalid TTL output voltage? |
| A. | 0.0–0.4 V |
| B. | 0.4–2.4 V |
| C. | 2.4–5.0 V |
| D. | 0.0–5.0 V |
| Answer» C. 2.4‚Äì5.0 V | |
| 22. |
What is the major advantage of ECL logic? |
| A. | very high speed |
| B. | wide range of operating voltage |
| C. | very low cost |
| D. | very high power |
| Answer» B. wide range of operating voltage | |
| 23. |
Why is a decoupling capacitor needed for TTL ICs and where should it be connected? |
| A. | to block dc, connect to input pins |
| B. | to reduce noise, connect to input pins |
| C. | to reduce the effects of noise, connect between power supply and ground |
| Answer» D. | |
| 24. |
A typical fan-out for most TTL is 9. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 25. |
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. | |
| 26. |
Why is the operating frequency for CMOS devices critical for determining power dissipation? |
| A. | At low frequencies, power dissipation increases. |
| B. | At high frequencies, the gate will only be able to deliver 70.7 % of rated power. |
| C. | At high frequencies, charging and discharging the gate capacitance will draw a heavy current from the power supply and thus increase power dissipation. |
| D. | At high frequencies, the gate will only be able to deliver 70.7 % of rated power and charging and discharging the gate capacitance will draw a heavy current from the power supply and thus increase power dissipation. |
| Answer» D. At high frequencies, the gate will only be able to deliver 70.7 % of rated power and charging and discharging the gate capacitance will draw a heavy current from the power supply and thus increase power dissipation. | |
| 27. |
The problem of interfacing IC logic families that have different supply voltages (VCC's) can be solved by using a: |
| A. | level-shifter |
| B. | tristate shifter |
| C. | decoupling capacitor |
| D. | pull-down resistor |
| Answer» B. tristate shifter | |
| 28. |
The output current capability of a single 7400 NAND gate when HIGH is called ________. |
| A. | source current |
| B. | sink current |
| C. | IOH |
| D. | source current of IOH |
| Answer» B. sink current | |
| 29. |
Can a 74HCMOS logic gate directly connect to a 74ALSTTL gate? |
| A. | Yes |
| B. | No |
| Answer» B. No | |
| 30. |
Fan-out is determined by taking the ________ result(s) of ________. |
| A. | smaller, |
| B. | larger, |
| C. | smaller, |
| D. | average, |
| Answer» D. average, | |
| 31. |
The basic part numbers of ICs are the same regardless of the manufacturer because digital logic ICs have been standardized. |
| A. | 1 |
| B. | |
| C. | 1 |
| D. | |
| Answer» B. | |
| 32. |
What should be done with unused inputs to a TTL NAND gate? |
| A. | let them float |
| B. | tie them LOW |
| C. | tie them HIGH |
| Answer» D. | |
| 33. |
The AND is the simplest of the gates, requiring the least amount of circuitry to implement in TTL. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 34. |
The most common TTL series ICs are: |
| A. | E-MOSFET |
| B. | 7400 |
| C. | quad |
| D. | AC00 |
| Answer» C. quad | |
| 35. |
Propagation delay in TTL is due to slow switching speeds. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 36. |
An open collector output can ________ current, but it cannot ________. |
| A. | sink, source current |
| B. | source, sink current |
| C. | sink, source voltage |
| D. | source, sink voltage |
| Answer» B. source, sink current | |
| 37. |
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 | |
| 38. |
Ten TTL loads per TTL driver is known as: |
| A. | noise immunity |
| B. | fan-out |
| C. | power dissipation |
| D. | propagation delay |
| Answer» C. power dissipation | |
| 39. |
The TTL HIGH level source current is higher than the LOW level sinking current. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 40. |
Why is a pull-up resistor needed for an open collector gate? |
| A. | to provide Vcc for the IC |
| B. | to provide ground for the IC |
| C. | to provide the HIGH voltage |
| D. | to provide the LOW voltage |
| Answer» D. to provide the LOW voltage | |
| 41. |
From the following specifications determine the fan-out for the logic family. |
| A. | HIGH state is 16, LOW state is 8 |
| B. | HIGH state is 8, LOW state is 16 |
| C. | HIGH state is 4, LOW state is 8 |
| D. | HIGH state is 8, LOW state is 4 |
| Answer» C. HIGH state is 4, LOW state is 8 | |
| 42. |
How is the speed–power product of a logic family determined? |
| A. | The propagation delay in s is multiplied by the power dissipation in mW. |
| B. | The propagation delay in ms is multiplied by the power dissipation in W. |
| C. | The propagation delay in ns is multiplied by the power dissipation in mW. |
| D. | The propagation delay in ns is multiplied by the power dissipation in W. |
| Answer» D. The propagation delay in ns is multiplied by the power dissipation in W. | |
| 43. |
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 | |
| 44. |
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 | |
| 45. |
The problem of different current requirements when CMOS logic circuits are driving TTL logic circuits can usually be overcome by the addition of: |
| A. | a CMOS inverting bilateral switch between the stages |
| B. | a TTL tristate inverting buffer between the stages |
| C. | a CMOS noninverting bilateral switch between the stages |
| D. | a CMOS buffer or inverting buffer |
| Answer» E. | |
| 46. |
If all inputs to a TTL NAND gate are low, what is the ON, OFF condition of each transistor in the circuit? |
| A. | Q1-ON, Q2-OFF, Q3-ON, Q4-OFF |
| B. | Q1-ON, Q2-ON, Q3-OFF, Q4-OFF |
| C. | Q1-OFF, Q2-OFF, Q3-ON, Q4-ON |
| D. | Q1-OFF, Q2-ON, Q3-OFF, Q4-ON |
| Answer» B. Q1-ON, Q2-ON, Q3-OFF, Q4-OFF | |
| 47. |
What is the difference between the 74HC00 series and the 74HCT00 series of CMOS logic? |
| A. | The HCT series is faster. |
| B. | The HCT series is slower. |
| C. | The HCT series is input and output voltage compatible with TTL. |
| D. | The HCT series is not input and output voltage compatible with TTL. |
| Answer» D. The HCT series is not input and output voltage compatible with TTL. | |
| 48. |
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 | |
| 49. |
How many 74LSTTL logic gates can be driven from a 74TTL gate? |
| A. | 10 |
| B. | 20 |
| C. | 200 |
| D. | 400 |
| Answer» C. 200 | |
| 50. |
The term buffer/driver signifies the ability to provide low output currents to drive light loads. |
| A. | 1 |
| B. | |
| C. | represent MOSFET devices utilizing either P-channel or N-channel devices exclusively within a given gate |
| D. | are enhancement-type CMOS devices used to produce a series of high-speed logic known as 74HC |
| Answer» C. represent MOSFET devices utilizing either P-channel or N-channel devices exclusively within a given gate | |