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
11. What is the difference between the 54XX and 74XX series of TTL logic gates?
- 54XX is faster.
- 54XX is slower.
- 54XX has a wider power supply and expanded temperature range.
- 54XX has a narrower power supply and contracted temperature range.
12. An open collector output can ________ current, but it cannot ________.
- sink, source current
- source, sink current
- sink, source voltage
- source, sink voltage
13. Why is a decoupling capacitor needed for TTL ICs and where should it be connected?
- to block dc, connect to input pins
- to reduce noise, connect to input pins
- to reduce the effects of noise, connect between power supply and ground
14. Using the above specifications, determine the amount of current in the output of a logic gate if the output of the gate is a logic LOW and connected to 4 inputs.
- 2 mA
- 4 mA
- 8 mA
- 18 mA
15. Using the schematic diagram of a TTL NAND gate, determine the state of each transistor (ON or OFF) when all inputs are high.
- Q1-ON, Q2-OFF, Q3-ON, Q4-OFF
- Q1-ON, Q2-ON, Q3-OFF, Q4-OFF
- Q1-OFF, Q2-OFF, Q3-ON, Q4-ON
- Q1-OFF, Q2-ON, Q3-OFF, Q4-ON
16. If all inputs to a TTL NAND gate are low, what is the ON, OFF condition of each transistor in the circuit?
- Q1-ON, Q2-OFF, Q3-ON, Q4-OFF
- Q1-ON, Q2-ON, Q3-OFF, Q4-OFF
- Q1-OFF, Q2-OFF, Q3-ON, Q4-ON
- Q1-OFF, Q2-ON, Q3-OFF, Q4-ON
17. Which of the following summarizes the important features of emitter-coupled logic (ECL)?
- low noise margin, low output voltage swing, negative voltage operation, fast, and high power consumption
- good noise immunity, negative logic, high-frequency capability, low power dissipation, and short propagation time
- low propagation time, high-frequency response, low power consumption, and high output voltage swings
- poor noise immunity, positive supply voltage operation, good low-frequency operation, and low power
18. Why is a pull-up resistor needed for an open collector gate?
- to provide Vcc for the IC
- to provide ground for the IC
- to provide the HIGH voltage
- to provide the LOW voltage
19. Why is a pull-up resistor needed when connecting TTL logic to CMOS logic?
- to increase the output LOW voltage
- to decrease the output LOW voltage
- to increase the output HIGH voltage
- to decrease the output HIGH voltage
20. The word "interfacing" as applied to digital electronics usually means:
- a conditioning circuit connected between a standard TTL NAND gate and a standard TTL OR gate
- a circuit connected between the driver and load to condition a signal so that it is compatible with the load
- any gate that is a TTL operational amplifier designed to condition signals between NMOS transistors
- any TTL circuit that is an input buffer stage