Low-voltage Bandgap voltage reference circuit and realizing method thereof

Abstract

The invention discloses a low-voltage Bandgap voltage reference circuit, which is characterized in that two BJT (Bipolar Junction Transistor) branches are differentially input to an operational amplifier adopting an NMOS (N-Mental-Oxide-Semiconductor) input pair structure; the output end of the operational amplifier is connected to a current mirror, and voltages on the two BJT branches are enabled to be equal by utilizing deep negative feedback; the base voltage of a shared base BJT in the two BJT branches are adjusted in a self-adaptive mode according to the work conditions of NMOS input pair in the operational amplifier, so currents of the two BJT branches are controlled, and the operational amplifier is enabled to normally work; and the output voltage of the Bandgap voltage reference circuit is generated in a mirror image mode. The invention also discloses a realizing method of the low-voltage Bandgap voltage reference circuit, through the scheme disclosed by the invention, the input voltage of the Bandgap voltage reference circuit is reduced, the Bandgap voltage reference circuit is enabled to work under the lower input voltage, and the deviation of the operational amplifier is prevented from being amplified.

Description

technical field [0001] The invention relates to voltage reference source technology, in particular to a low-voltage bandgap (Bandgap) voltage reference circuit and a realization method thereof. Background technique [0002] As a basic unit circuit, the voltage reference source plays an extremely important role in circuits such as digital / analog (D / A), analog / digital (A / D) converters and SDRAM. Among many types of voltage reference sources, the Bandgap voltage reference circuit is the most widely used. [0003] Traditional Bandgap voltage reference circuits generally have figure 1 and figure 2 The two structures shown, figure 1 Among them, P-type-metal-oxide-semiconductor (PMOS, P-Mental-Oxide-Semiconductor) P11, PMOS P12, and PMOS P13 constitute a cascode current mirror, which is used to mirror the current on each other's circuits, and PMOS P14, PMOS P15 and PMOS P16 form a cascode circuit. The positive input terminal of the operational amplifier (hereinafter referred t...

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Problems solved by technology

figure 2 In the Bandgap voltage reference circuit shown, the positive and negative input terminals of the op amp OP2 have the same voltage, and the resistance ratio of resistor R21 to resistor R23 is equal to the resistance ratio of resistor R22 to resistor R24. For example, resistor R21 can be two resistors R22 connected in series , the resistor R23 can be two resistors R24 in series, etc.; the operational amplifier OP2 adopts a PMOS input pair structure, and the minimum input voltage required for the normal operation of the operational amplifier OP2 is small, but due to the existence of the resistor R21 and the resistor R22, the amplification The deviation (offset) of the op amp OP2 is reduced, which is not conducive to the application

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