Demultiplexer
A demultiplexer, or demux, is a device that takes a single input and directs it to one of several output lines. In physics, demultiplexers are used to separate a single input signal into multiple channels, allowing for the transmission of data to different destinations. This process is essential for various applications, including telecommunications and data processing.
3 Key excerpts on "Demultiplexer"
eBook - ePubSemiconductor Basics
A Qualitative, Non-mathematical Explanation of How Semiconductors Work and How They are Used
- George Domingo(Author)
- 2020(Publication Date)
- Wiley(Publisher)
...12 VLSI Components OBJECTIVES OF THIS CHAPTER We are now ready to talk about more complex electronic system components that are an integral part of microprocessors, computers, cell phones, and many other devices that I discuss in the next couple of chapters. These include multiplexers that select signals from multiple inputs, Demultiplexers that do the opposite, registers that store intermediate results, and all type of memories. We already have all the background we need to understand how these larger components work. 12.1 Multiplexers A multiplexer is a component with many inputs and one output. We call it a MUX for short. It is an essential component in almost all large electronic systems. The MUX is basically a selector switch, as I show in Figure 12.1. The selector switch or the rotary switch on the left selects which of the four inputs I want to connect to the output, O. I show the schematic symbol of an electronic multiplexer on the right. In addition to the four inputs and the output, the symbol has two other inputs, the control inputs a and b, which determine the position of the switch arm and selects which of the inputs goes to the output. Figure 12.1 A MUX selects one of the many inputs, like a rotary switch. The symbol for a MUX is on the right. Figure 12.2 A 2 to 1 MUX implementation using two ANDs, one NOT, and one OR module with the truth table on the right. The electronic circuit that performs the MUX function is not that complicated (Figure 12.2). Recall that the output of an AND circuit is 1 only if the two inputs are 1, and 0 otherwise. Suppose now that I set the control line, a, to 1. Then one of the inputs of AND2 is always 0 and therefore the output of the AND2 is always zero no matter what the value of input B is. The output of AND1 is 1 only when input A is 1, and zero otherwise. That is what the first four rows of the truth table tell us. The output, column O, is equal to the input A, no matter what the value of input B is...
eBook - ePub- Allan Bonnick(Author)
- 2014(Publication Date)
- Routledge(Publisher)
...The MUX works at very high speed and can switch between the inputs for as long as is required. This means that a single processor can be used for all instruments, instead of a separate one for each. Figure 9.17 shows the relation between the various parts of an electronic instrument display. The Demultiplexer (demux) takes the single output from the processor (ECU) and directs it to the appropriate instrument. It works in much the same way as the multiplexer except that it takes one data input, from the ECU, and directs it to the required gauge. This means that the ECU is processing sensor inputs in a sequence, and selecting a gauge to send the output to, in the same sequence, which means that the gauge inputs are interrupted. It has to be remembered that the multiplexer and the ECU may work at very high speeds and, depending on the type of instrument used for the gauge display, this means that the intermittent nature of the gauge input does not produce discernible fluctuation on the gauges. For example, a fuel contents gauge can operate by sampling the sensor input every few seconds, whereas the speedometer will need to sample the sensor input several times a second. Such timing operations are easily performed by the timer section of the ECU. Fig. 9.17 An instrument system using a multiplexer Another vehicle use the multiplex concept As the number of electronically controlled systems on vehicles has increased so has the number of circuits, and this has led to a significant increase in the total length of wire used on the average vehicle. Coupled with the increased use of wire is an increase in the complexity of circuits. In order to overcome these difficulties, systems have been developed in which a power line (bus) carries the electricity supply around the vehicle and output devices, such as motors, solenoids, etc. are connected to the power line, as and when required, by coded data signals which are transmitted via a signal line (data bus)...
eBook - ePub- Steve Moore(Author)
- 2020(Publication Date)
- CRC Press(Publisher)
...Thus, a four-channel differential MUX (DG509A) is created from a single-ended eight-channel MUX (DG508A). One of the address bits is eliminated, because the decoding is reduced from one of eight to one pair of four. An additional drain output is required because the two four-channel MUXes have separate outputs. Differential MUXes are useful for handling pairs of signals that are routed together, such as inputs to data acquisition systems for precision instrumentation, or for audio signals that are handled differentially to eliminate common-mode noise, or for signals that travel in pairs such as stereo audio signals. 2.2.4 Multiplexer/Amplifiers The level of integration continues to increase with the development of the MUX/amplifier function. These devices have been developed to meet the need for buffers in high frequency systems like video routing equipment. Buffers are usually required when MOS switches are used, at the input of the switch because of the capacitive loading of the switch, and at the output because of the need to drive following stages that have resistive and/or capacitive loads. Amplifiers are also used at the output of MUXes to provide gain to compensate for signal losses in the MUX or in previous stages of the system. An example of a MUX with a built-in output amplifier is the MAX455 (Figure 2.13). Figure 2.13 The MAX455 8-Channel MUX/AMP combines CMOS “T” switches with a wideband amplifier. (From Maxim Integrated Products, 1989 IC Data Book, © 1989. Used with permission.) 2.3 Switch Arrays A recent development in analog switches is the creation of arrays of switches that are intended for specific applications. The DG485 eight-channel serially controlled analog switch array (Figure 2.14) is an example. The DG485 switch array is useful for one specific class of applications, that is, systems that use a serial data format for controlling analog signals...
