Band-gap reference circuit with low offset voltage and high power supply rejection ratio

Abstract

The invention discloses a band-gap reference circuit with a low offset voltage and high power supply rejection ratio. The band-gap reference circuit comprises a voltage modulation unit (1), a band-gapcore unit (2) and an operational amplifier unit (3). The voltage modulation unit shields a noise on a power supply VDD, generates a modulation voltage VREF to supply power to the band-gap core unit and the operational amplifier unit, and improves a power supply rejection ratio; the band-gap core unit generates a band-gap reference voltage VBG with a zero temperature coefficient; and the operational amplifier unit ensures that a first clamping voltage VA is equal to a second clamping voltage VB, and outputs a feedback voltage VF to the band-gap core unit to form a feedback loop so as to ensurestability of the band-gap reference voltage VBG. By adopting the voltage modulation unit, the power supply rejection ratio is effectively improved; and an offset voltage of the operational amplifierunit is small, and precision of the band-gap reference voltage is improved. The circuit has characteristics of the low offset voltage and the high power supply rejection ratio, and can be used for ananalog integrated circuit.

Description

technical field [0001] The invention belongs to the technical field of analog integrated circuits, and relates to a bandgap reference circuit with low offset voltage and high power supply rejection ratio. Background technique [0002] In the field of analog integrated circuit and mixed signal integrated circuit design, the reference voltage source is one of the important components. The reference voltage source is one of the core modules of the analog circuit. Its main function is to provide a reference voltage for other modules of the chip that does not vary with temperature and supply voltage. Its performance affects the performance of the entire chip. [0003] Traditional bandgap voltage references such as figure 1 As shown, the basic principle is to superimpose the voltage with positive temperature coefficient and the voltage with negative temperature coefficient with a certain coefficient to obtain a bandgap voltage with approximately zero temperature coefficient, and ...

AI Technical Summary

Problems solved by technology

[0008] (1) In the traditional bandgap reference voltage source, the operational amplifier is used to ensure that the voltages of M and N points are equal, and the offset voltage Vos of the operational amplifier A will seriously affect the accuracy of the bandgap reference voltage VBG;

[0009] (2) The offset voltage of the operational amplifier A also has a temperature coefficient, which will affect the temperature coefficient of the bandgap reference voltage VBG;

[0010] (3) In the traditional bandgap reference voltage source technology, the operational amplifier A is powered by the power supply voltage, the noise on the power supply will directly affect the accuracy of the bandgap reference voltage VBG, and it is difficult to achieve a high power supply rejection ratio;

The voltage cascading will limit the input voltage range, and the large filter capacitor on the chip will occupy a large chip area

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