A multiplexer, selector or scanner is essentially a set of switches used to connect one of a number of alternative inputs to a single device in sequence, in order to make more efficient use of an expensive component. A digital multiplexer may be used to select one digital word or byte from a number of sources, but here we are primarily concerned with analogue multiplexers as these are much more common in data acquisition systems. In these systems, the most expensive component may be the signal conditioning, but it is most likely to be the high resolution A/D converter and the computer. Therefore, it is very common to multiplex a number of sensors to one converter. How this affects the positions of sample and hold circuits and the timing of the various operations is discussed in Chapter 10, but this chapter considers a multiplexer as a component by itself. A system may also include a demultiplexer to connect the output of a D/A converter to a number of different points.
KeywordsStray Capacitance Reed Switch Analogue Multiplexer Maximum Slew Rate Oxide Semiconductor Field Effect Transistor
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