temperature sensor signal is very weak,For several times the temperature change,The thermistor temperature detector produces a corresponding analog voltage change of at most hundreds of millivolts.Therefore, the typical temperature analog output voltage is only within the mV range.If you do not use the gain circuit,The transmission range of the analog-to-digital converter is usually ± VREF.In order to optimize the performance of analog-to-digital converters,The analog input range should be used.
The temperature sensor signal needs to be transmitted to the controller,It needs to be equipped with a "signal amplifier"There are special terminals on the transmitter.The output of the transmitter is more common is 4-20mA current signal,And your control room in the digital instrument or acquisition system AI connection;When using this type of temperature sensor to measure the temperature,The importance of gain is exceptionally prominent.If the temperature sensor does not have any gain,Then the analog-to-digital converter full-scale range is only a small part of the use,This will lose the resolution.
The temperature sensor signal needs to work normally,Must give him a peripheral circuit,Including the addition of voltage, the amount of change and resistance value corresponding,And far-reaching ability - these are done by the temperature transmitter.