Logic Families and Their Characteristcs Questions and Answers
Logic Families and Their Characteristics questions with answers are an important part of digital electronics aptitude. Understanding TTL, CMOS, and ECL logic families is vital for solving problems in timing, voltage levels, and power consumption. Exams like GATE, DRDO, and ISRO frequently include such questions to test a student’s grasp of digital circuit behavior. This section provides well-structured aptitude questions with step-by-step solutions, helping students compare logic families and analyze their performance parameters. Strengthen your understanding of digital systems through these practice problems and prepare effectively for competitive exams.
Logic Families and Their Characteristcs
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47 questions
21. 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.
- 10%, 90%, 90%, 10%
- 90%, 10%, 10%, 90%
- 20%, 80%, 80%, 20%
- 10%, 70.7%, 70.7%, 10%
22. The term buffer/driver signifies the ability to provide low output currents to drive light loads.
- TRUE
- FALSE
23. PMOS and NMOS ________.
- represent MOSFET devices utilizing either P-channel or N-channel devices exclusively within a given gate
- are enhancement-type CMOS devices used to produce a series of high-speed logic known as 74HC
- represent positive and negative MOS-type devices, which can be operated from differential power supplies and are compatible with operational amplifiers
- None of the above
24. Why is the operating frequency for CMOS devices critical for determining power dissipation?
- At low frequencies, power dissipation increases.
- At high frequencies, the gate will only be able to deliver 70.7 % of rated power.
- At high frequencies, charging and discharging the gate capacitance will draw a heavy current from the power supply and thus increase power dissipation.
- 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.
25. Ten TTL loads per TTL driver is known as:
- noise immunity
- fan-out
- power dissipation
- propagation delay
26. The problem of different current requirements when CMOS logic circuits are driving TTL logic circuits can usually be overcome by the addition of:
- a CMOS inverting bilateral switch between the stages
- a TTL tristate inverting buffer between the stages
- a CMOS noninverting bilateral switch between the stages
- a CMOS buffer or inverting buffer
27. Totem-pole outputs ________ be connected ________ because ________.
- can, in parallel, sometimes higher current is required
- cannot, together, if the outputs are in opposite states excessively high currents can damage one or both devices
- should, in series, certain applications may require higher output voltage
- can, together, together they can handle larger load currents and higher output voltages
28. The high input impedance of MOSFETs:
- allows faster switching
- reduces input current and power dissipation
- prevents dense packing
- creates low-noise reactions
29. The output current capability of a single 7400 NAND gate when HIGH is called ________.
- source current
- sink current
- IOH
- source current of IOH
30. The time needed for an output to change from the result of an input change is known as:
- noise immunity
- fan-out
- propagation delay
- rise time