A mechanical switch cannot perform this task efficiently. Therefore, multiplexer is used to perform high speed switching are constructed of electronic components.
Multiplexers can handle two type of data i. For analog application, multiplexer are built using relays and transistor switches. For digital application, they are built from standard logic gates.
The multiplexer used for digital applications, also called digital multiplexer, is a circuit with many input but only one output. By applying control signals also known as Select Signals , we can steer any input to the output.
Some of the common types of multiplexer are 2-to-1, 4-to-1, 8-to-1, to-1 multiplexer. Following figure shows the general idea of a multiplexer with n input signal, m control signals and one output signal.
The 4-to-1 multiplexer has 4 input bits, 2 control or select bits, and 1 output bit. The four input bits are D0,D1,D2 and D3. Only one of this is transmitted to the output Y. The output depends on the values of A and B, which are the control inputs. The control input determines which of the input data bit is transmitted to the output.
Multiplexer are used in various fields where multiple data need to be transmitted using a single line. Following are some of the applications of multiplexers —. This is just an introduction to the concept of Multiplexer. Demultiplexer means one to many.
A demultiplexer is a circuit with one input and many outputs. By applying control signal, we can steer any input to the output. Few types of demultiplexer are 1-to 2, 1-to-4, 1-to-8 and 1-to 16 demultiplexer.
Following figure illustrate the general idea of a demultiplexer with 1 input signal, m control signals, and n output signals. The 1-to-4 demultiplexer has 1 input bit, 2 control or select bits, and 4 output bits. An example of 1-to-4 demultiplexer is IC The 1-to-4 demultiplexer is shown in figure below-.
The input bit is labelled as Data D. This data bit is transmitted to the selected output lines, which depends on the values of A and B, the control or Select Inputs. In this section, let us implement 16x1 Multiplexer using 8x1 Multiplexers and 2x1 Multiplexer. We know that 8x1 Multiplexer has 8 data inputs, 3 selection lines and one output. Whereas, 16x1 Multiplexer has 16 data inputs, 4 selection lines and one output.
So, we require two 8x1 Multiplexers in first stage in order to get the 16 data inputs. Since, each 8x1 Multiplexer produces one output, we require a 2x1 Multiplexer in second stage by considering the outputs of first stage as inputs and to produce the final output. Let the 16x1 Multiplexer has sixteen data inputs I 15 to I 0 , four selection lines s 3 to s 0 and one output Y. The Truth table of 16x1 Multiplexer is shown below.
We can implement 16x1 Multiplexer using lower order Multiplexers easily by considering the above Truth table. The block diagram of 16x1 Multiplexer is shown in the following figure. The outputs of first stage 8x1 Multiplexers are applied as inputs of 2x1 Multiplexer that is present in second stage. The other selection line, s 3 is applied to 2x1 Multiplexer. Therefore, the overall combination of two 8x1 Multiplexers and one 2x1 Multiplexer performs as one 16x1 Multiplexer.
Gowthami Swarna. Asif Hussain. John Shea. Raghu Pandey. Sebastian Sulinski. Juan Galvan. Digital Circuits - Multiplexers Advertisements. Previous Page. Next Page. Useful Video Courses. Digital Electronics Lectures
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