Improved voltage regulator

Abstract

The invention provides a voltage regulator, which includes a bandgap reference voltage source circuit, a power transistor, a first voltage dividing resistor, a second voltage dividing resistor and an error amplifier. The bandgap reference voltage source circuit includes an operational amplifier, a third resistor, a first intermediate node, a second intermediate node, a sampling switch, a first capacitor, a filter, a reference voltage output terminal, a switch combination circuit, and N bipolar Transistors and control circuits. In the present invention, in different time periods, the switch combination circuit enables N bipolar transistors to be connected to the second intermediate node B in turn one by one, so that the remaining (N-1) bipolar transistors are connected in parallel to the first The middle node A, through this rotation, the mismatch between bipolar transistors can be averaged out, so that higher output voltage accuracy can be achieved, making it less affected by the mismatch of bipolar transistors and packaging stress .

Description

【Technical field】 [0001] The invention relates to the technical field of electronic circuits, in particular to an improved voltage regulator. 【Background technique】 [0002] Bandgap reference voltage sources are widely used in various analog circuits. In practical applications, high-precision bandgap reference voltage sources are favored. Please refer to figure 1 As shown, it is a schematic circuit diagram of a bandgap reference voltage source in the prior art, which includes resistors R1, R2, R3, bipolar transistors PNP transistors Q1, Q2, and an operational amplifier OP. Generally, the emitter area of ​​Q1 is designed to be larger than that of Q2, for example, its ratio is K:1. In order to achieve a better matching effect in actual design, Q1 is generally designed as K PNP transistors in parallel with Q2. In one example K=4. Generally, the resistance values ​​of resistors R1 and R2 are designed to be the same, and are designed to be M times the resistance value of R3, ...

AI Technical Summary

Problems solved by technology

[0003] Although Q1 is designed as K transistors in parallel with Q2, there is a mismatch between each transistor in Q1 and Q2, that is, when mass production, there will be differences between chips, and these differences will cause inaccurate VBG, And this difference will vary due to package stress effects

Even at the wafer or chip stage, VBG is adjusted accurately through trimming technology, but after packaging, due to the influence of packaging stress, there are deviations between chips

[0004] Therefore, due to the deviation of the generated bandgap reference voltage VGB, the final voltage value formed by the voltage regulator using such a bandgap reference voltage source is also inaccurate.

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