Multiplexer, Decoders, and Programmable Logic Devices-數位邏輯設計筆記

一定愛配王俊堯教授開放課程食用:課程連結

Multiplexer, Decoders, and Programmable Logic Devices

Mutiplexer(多工器, Mux)

• Reference:link

Introduction to Mux

• Mux is also known as Data Selector.

• A to mux needs n control inputs.

  

• The structure of to mux.

  

• The structure of a quad multiplexer

  

Using 4-1 mux to realize 3-variable function

• A 4-1 mux is able to realize a function with 3-variable which has the same general form as the 4-1 mux.
• Ex

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Using a 8-1 mux to realize 4-variable function

• A 8-1 mux is able to realize a function with 4-variable which has the same general form as the 8-1 mux.
• Ex
  

Demultiplexer(A brief introduction)

• Introduction of Demux

Three-State Buffers(Tri-state buffer)

• Reference:link

Introuduction to Buffer

• Buffer is a gate that can be used to increase the strength of a signal, to increase the drving capibility of a gate output.

• It can also be used to shorten or extend the delay of a circuit.

• Buffer can actually be recognized as two NOT gates.

• The truth table of buffer

  

Introduction to Tri-State Buffer

• Tri-state buffer is a gate that can be thought of as a switch.

• It has three output states => 0, 1, and z.

  • 0 => LOW
  • 1 => HIGH
  • Z => High Impedance, can be recognized as an open circuit.

• There are 4 genres of Tri-state buffer

  • Active High

  • Inverting Active High

    

  • Active Low

    

  • Inverting Active Low

    

• Data selection can be done by combining mutiple tri-state buffers.

  

  • The truth table of connecting two tri-state buffers(X => unknown).

    

Application of tri-state buffer

• Bus

  • Tri-state Buffer can be used to isolate devices and circuits from the data bus and one another.

  

• Chip I/O

  • Tri-state Buffer enables a pin on an IC to function bidirectionally.

  

Decoder

2023/05/14 第9F講 Multiplexers, Decoders, and Programmable Logic Devices