What is the band gap reference_The advantages of the band gap reference circuit - This article first introduces what the band gap reference is, and then analyzes the principle of the band gap reference. What is the bandgap reference?

The classic bandgap reference uses the sum of a voltage proportional to temperature and a voltage inversely proportional to temperature. The temperature coefficients of the two cancel each other out to achieve a temperature-independent voltage reference, which is about 1.25V. Because its reference voltage is similar to the band gap voltage of silicon, it is called a band gap reference. What is actually utilized is not the bandgap voltage. Nowadays, the output voltage of some bandgap reference structures is not consistent with the bandgap voltage.

The principle of band gap reference

Analog circuits widely include voltage references and current references. This reference is a DC quantity, which has a small relationship with power supply and process parameters, but a definite relationship with temperature.

The purpose of generating a reference is to establish a DC voltage or current with determined temperature characteristics that is independent of power supply and process. In most applications, the required temperature relationship takes one of three forms:

1) Proportional to absolute temperature;

2) Constant Gm characteristics, that is, the transconductance of some transistors remains constant;

3) It has nothing to do with temperature.

The main problem that needs to be solved to realize the reference voltage source is how to improve its temperature suppression and power supply suppression, that is, how to realize a structure that has a definite relationship with temperature and is basically independent of power supply. Since in reality semiconductors have almost no temperature-independent parameters, only some parameters with positive and negative temperature coefficients can be found. Through appropriate combinations, temperature-independent quantities can be obtained, and these parameters have nothing to do with the power supply.

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