Low pressure difference linearity voltage stabilizer for enhancing performance by amplifier embedded compensation network

Abstract

A low-dropout linear regulator that uses the built-in compensation network of the amplifier to improve performance. By building a compensation network composed of resistors and capacitors in the amplifier, it can be used in the feedback loop without changing the quiescent operating point of the amplifier and without increasing the quiescent current. One or more zero-pole pairs whose zero frequency is lower than the pole frequency are added to the transfer function of the circuit. The frequency of these zero-pole pairs can be accurately determined to enhance the stability of the feedback loop of the low-dropout linear regulator and expand the loop. The unity gain bandwidth increases the phase margin and DC and low frequency gain of the loop, thereby improving the performance of the low dropout linear regulator.

Description

technical field [0001] The invention relates to a low-dropout linear voltage stabilizer, in particular to a low-dropout linear voltage stabilizer which utilizes a built-in compensation network of an amplifier to improve performance. Background technique [0002] Closed-loop negative feedback systems are commonly used in linear integrated circuits. For example, in a low-dropout voltage regulator (LDO, Low-Dropout Voltage Regulator), it is necessary to use a feedback loop to obtain a stable output voltage. According to the Nyquist criterion, in order to ensure the stability of the closed-loop system, the phase shift of the loop at unity gain should be less than 180 degrees. However, in actual circuit design, it is generally required that the phase shift of the loop at unity gain is less than 135 degrees (that is, the phase margin is greater than 45 degrees). In most cases, control of the phase shift is achieved by including a compensation circuit in the feedback loop. [00...

AI Technical Summary

Problems solved by technology

A lower UGF not only causes the loop to respond slower, but also limits the loop's DC gain

If the LDO's loop gain is low, its output voltage accuracy will be reduced accordingly

[0012] 2. Due to the limitations of working conditions, manufacturing process changes and model accuracy, the positions of poles P3 and P4 cannot be accurately calculated during circuit design, which increases the difficulty of frequency compensation

In order to ensure that the designed circuit can work stably, it is usually necessary to further sacrifice the performance of the LDO

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