Which of the following logic circuits is the fastest

Electrical Engineering XYZ MCQs

Which of the following logic circuits is the fastest;

  1. TTL
  2. RTL
  3. DTL
  4. All have same speed

Correct answer: 1. TTL


  1. TTL (Transistor-Transistor Logic): TTL logic circuits are composed of bipolar junction transistors and resistors. They are known for their relatively high speed compared to other logic families like RTL (Resistor-Transistor Logic) and DTL (Diode-Transistor Logic). TTL circuits typically operate in the range of tens of nanoseconds (ns) or less, making them one of the fastest among the traditional logic families.
  2. RTL (Resistor-Transistor Logic): RTL logic circuits use resistors for input and output coupling and transistors for logic functions. RTL circuits tend to have slower switching speeds compared to TTL due to the nature of their design, involving more components and higher resistance.
  3. DTL (Diode-Transistor Logic): DTL logic circuits use diodes for input coupling and transistors for amplification and logic functions. DTL circuits are generally slower than TTL due to the presence of diodes, which introduce additional capacitance and delay in the signal propagation.

Therefore, among the options given, TTL logic circuits are the fastest due to their simpler design and use of bipolar transistors, which enable faster switching speeds compared to RTL and DTL circuits.

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