Low dropout linear regulator, method for improving stability of low dropout linear regulator and phase-locked loop

Abstract

The embodiment of the invention discloses a low dropout linear regulator, a method for improving the stability of the low dropout linear regulator and a phase-locked loop. The low dropout linear regulator comprises a reference voltage source, an error amplifier, an adjustment circuit, a load, a first compensating circuit and a second compensating circuit. The first compensating circuit is coupled with the adjustment circuit and used for adjusting a dominant pole and a secondary dominant pole of the low dropout linear regulator to adjust the phase margin. The second compensating circuit is used for adjusting the dominant pole of the low dropout linear regulator on the basis that the dominant pole and the secondary dominant pole of the low dropout linear regulator are adjusted by the first compensating circuit, further increasing the secondary dominant pole to adjust the phase margin and adjusting the gain bandwidth product of the low dropout linear regulator. By means of the low dropout linear regulator, the value of the gain bandwidth product and the dominant pole can be remarkably reduced, the secondary dominant pole can be increased, and therefore the error amplifier has the better noise performance.

Description

technical field [0001] The invention relates to the field of semiconductors, in particular to a low-dropout linear voltage regulator, a method for increasing its stability and a phase-locked loop. Background technique [0002] A Phase Locked Loop (PLL for short) refers to an automatic control closed-loop system composed of a Phase Detector, a Loop Filter, and a Voltage Control Oscillator (VCO). . Because PLL can complete the phase synchronization of two electrical signals, it is widely used in fields such as broadcast communication, frequency synthesis, automatic control and clock synchronization. Since power supply noise and fluctuations will affect the stability of the PLL, in actual use, it is usually necessary to use a low dropout linear regulator (LDO for short) to overcome the influence of power supply noise and fluctuations on the PLL, to ensure that the PLL and other noise-sensitive characteristics of the circuit. [0003] Such as figure 1 As shown, the existing ...

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Problems solved by technology

[0006] Embodiments of the present invention provide a low-dropout linear voltage regulator, a method for increasing its stability, and a phase-locked loop to overcome the problem of poor noise performance of the existing low-dropout linear voltage regulator

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