Temperature detection using diode multiplexing.Human Body Infrared Temperature Sensor

　　Where there is electricity, heat is generated, and where heat is generated, temperature (the most widely sensed physical variable) needs to be sensed. Our so-called temperature is a measurement of material thermal energy, and there are many sensors that can measure it, from very low costs, limited ranges to complex and professional units. In some cases, it is difficult to decide which sensor to use because there are many feasible options, and sometimes only one or two sensors can make a choice. Not surprisingly, the expected temperature itself (high, low, and span), required accuracy and resolution, cost (of course), and other factors are used as functions.

　　You may be thinking: I already know this, so please fully understand physics. On the other hand, if you are not familiar with this method, you can conduct a brief review or tutorial online.

　　The temperature dependence of diode junctions is both a curse and a blessing. Of course, this will seriously affect the basic performance of semiconductor devices, as current and voltage can change, and the temperature coefficient (tempco) is a carefully studied data sheet number. IC designers use many clever topology structures to minimize their impact and even better develop solutions so that the changes they cause will eliminate them.

　　Although this temperature sensitivity hinders the performance of discrete devices and ICs, it can also be used for temperature sensing. Many analog and digital devices use basic on-chip junctions to detect their own chip temperature, and even call shutdown when the chip temperature is too high. This eliminates the need for individual sensors and is a cost-effective solution for self monitoring.

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