Monday, July 21, 2008

Digital Logic Families

Information about digital logic families is the commonly asked question in many entrance exams for embedded training course. The most popular digital logic families are transistor-transistor logic (TTL), emitter-coupled logic (ECL), metal-oxide semiconductor (MOS) and complementary metal-oxide semiconductor. Now let us see about the features of each of these families.

  • The TTL is a logic family that has been in operation for a long time and is considered as standard. They consume more power than an equivalent CMOS device but consume less power when compared to ECL.
  • The ECL logic family has an advantage in systems requiring high speed operations. The ECL gates use differential amplifier configuration at the input state. They usually operate with negative power supplies.
  • The MOS is suitable for circuits that need high component density.
  • The CMOS is preferable in systems requiring low power consumption and they are used for VLSI design.

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