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What is the role of operational amplifiers?

Latest Updated:03/01/2006

Question:

What is the role of operational amplifiers?

Answer:

Elements in our environment such as wind, light, sound, temperature, and humidity change quantitatively on a continual basis. In other words, they are analog values. On the other hand, the processing executed in most devices we use these days is digital. Some form of analog signal processing is therefore required to handle the analog values input to these devices. This analog signal processing is mainly carried out by operational amplifiers.
Let's use a concrete example of analog signal processing wherein the land surface temperature is measured at regular intervals and recorded by a device. First, the land surface temperature is converted into a voltage using a temperature sensor (this is also an analog value). If this voltage is extremely small, there is the risk that the fluctuations cannot be observed, so the voltage must be amplified. This amplification can be done using an operational amplifier (which has the function of obtaining the difference between the signal converted into a voltage and the reference signal, and amplifying this difference through a peripheral circuit of the operational amplifier). Then, the amplified voltage is converted into digital values through A/D conversion, which are then processed by the microcomputer.



As another operational amplifier application example, let's consider an application that measures and records the temperature difference between two points (land surface and 2 m above ground). Likewise, an operational amplifier can be used to obtain the difference (subtraction) between the temperatures measured by two temperature sensors at two points, as follows.



Operational amplifiers also have other functions, such as addition, differentiation, and integration.

In addition to the operational amplifier, a comparator is used to interface (transfer data) to a digital circuit. For the role of a comparator, refer to Comparator Basics.
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