LDO (low dropout regulator) circuit and LDO implementing method

A circuit and compensation circuit technology, applied in the direction of adjusting electrical variables, control/regulation systems, instruments, etc., can solve problems such as failure to follow, LDO circuit stability decline, etc.

Active Publication Date: 2018-02-13
GUANGZHOU HUIZHI MICROELECTRONICS
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the pole frequency at the output node is generally very easily affected by the output current, so when the output current changes greatly, the pole frequency at the output node also changes greatly, so the zero frequency of the LDO circuit cannot follow the LDO circuit The frequency of the pole located at the output node in the middle causes the stability of the LDO circuit to degrade

Method used

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  • LDO (low dropout regulator) circuit and LDO implementing method
  • LDO (low dropout regulator) circuit and LDO implementing method
  • LDO (low dropout regulator) circuit and LDO implementing method

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Embodiment Construction

[0039] The circuit structure of the existing NMOS LDO circuit in integrated circuit design is briefly introduced above, and the working principle of the NMOS LDO circuit will be described in detail below.

[0040] figure 1 In the circuit shown, according to the pole frequency formula at the output node It can be seen that when the output current is small, the load Rload is large, and the transconductance gmp of the NMOS transistor M1 is small. At this time, the pole is located at a low frequency; when the output current is large, the load Rload is small, and the transconductance gmp of the NMOS transistor M1 is small. The transconductance gmp is larger, at this time, the pole is located at a higher frequency. Regardless of whether the pole is located at a lower frequency or a higher frequency, it will affect the stability of the NMOS LDO circuit, especially when the frequency of the pole is less than the unity gain bandwidth of the loop in the NMOS LDO circuit. Compensation ...

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Abstract

The invention discloses an LDO (low dropout regulator) circuit, comprising an LDO main circuit, a detection circuit and a compensation circuit, wherein the LDO main circuit is used for reducing an input voltage according to a reference voltage to obtain a reduced voltage and performing feedback processing to keep the reduced voltage constant so as to obtain an output voltage; the detection circuitis used for acquiring compensation current information based on output current of the LDO main circuit, wherein the compensation current information is used for characterizing changes in the output current; the compensation circuit is used for regulating frequency of a zero point of the LDO main circuit according to the compensation current information so that during operating of the LDO main circuit, the frequency of the zero point is kept matched with that of an extreme point of the LDO main circuit at an output node, and the constant output voltage is maintained. The invention also discloses an LDO implementing method.

Description

technical field [0001] The invention relates to the technical field of semiconductor integrated circuits, in particular to a low dropout linear regulator (LDO, Low Dropout Regulator) circuit and a method for realizing the LDO. Background technique [0002] Traditional linear regulators generally require the input voltage to be at least 2V higher than the output voltage, otherwise the linear regulator cannot work properly. However, in some cases, such conditions are relatively harsh. For example, in an application environment where the input voltage is 5V and the output voltage is 3.3V, the voltage difference between the input voltage and the output voltage is only 1.7V. Obviously, the voltage difference of 1.7V It does not meet the working conditions of traditional linear regulators. Therefore, in response to this situation, chip manufacturers have developed LDO-like voltage conversion chips. Moreover, because the LDO has outstanding advantages such as simple structure, lo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G05F1/575
CPCG05F1/575
Inventor 苏强彭振飞奕江涛
Owner GUANGZHOU HUIZHI MICROELECTRONICS
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