Multiplex circuit, error amplifier and multiplexed output low dropout linear regulator

Abstract

The invention discloses a multiplex circuit, an error amplifier and a multiplexed output low dropout linear regulator. The multiplexed output low dropout linear regulator comprises the error amplifier, the multiplex circuit and a feedback circuit and is characterized in that the error amplifier receives feedback voltage provided by the multiplex circuit through the feedback circuit, compares the received feedback voltage with reference voltage and outputs amplification signals to the multiplex circuit; the error amplifier outputs the voltage signals to provide bias voltage for the multiplex circuit; the multiplex circuit compares the amplification signals output by the error amplifier with the reference voltage to convert the amplification signals into the N voltage signals and outputs the voltage signals through N voltage output ends after amplifying the voltage signals. The LDO linear adjustment rate and the power voltage rejection ratio can be effectively increased, output noise and chip area are reduced, application complexity and cost are reduced, and application prospects are good.

Description

technical field [0001] The invention relates to a low-dropout linear voltage stabilizer, in particular to a multiplexing circuit, an error amplifier and a multi-channel output low-dropout linear voltage stabilizer. Background technique [0002] A low-dropout linear regulator (LDO) is a circuit that can provide clean DC power. It has the characteristics of low dropout voltage, low cost, small size, and high power supply rejection ratio (PSRR). It can be used in mobile phones and notebook computers. , communications, automotive electronics, consumer electronics and other fields. LDO is mainly composed of error amplifier, adjustment tube and voltage feedback resistor. The error amplifier, the adjustment tube, and the voltage feedback resistor form a voltage negative feedback to output a stable DC voltage. With the development of science and technology, integrated circuits have more and more functions and higher integration. A functional chip usually needs to integrate multipl...

AI Technical Summary

Problems solved by technology

Traditional LDOs usually require external capacitors to compensate the phase margin. If multiple LDOs are integrated on-chip, each LDO needs an external capacitor, which increases the complexity and cost of the application. There is also a method to compensate the phase margin inside the chip through capacitor multiplication technology. , but this method is limited to single-output LDOs. If multiple outputs are required, multiple error amplifiers, adjustment tubes and voltage feedback resistors are required, and the chip area is large

The power supply voltage of the error amplifier in the traditional LDO is directly provided by the input power supply, and the PSRR is determined by the loop gain. Increasing the loop gain can improve the PSRR of the LDO, but too high loop gain also means that the compensation of the phase margin becomes more difficult. Difficult, so usually the loop gain of the LDO is less than 60dB, and the PSRR is not high

figure 1 and figure 2 Shown is the traditional LDO circuit structure, figure 1 The LDO is composed of error amplifier AMP, adjustment tube M 11 , voltage feedback resistor R 11 , R 21 , external compensation capacitor C OUT and equivalent resistance R ESR Composition, requires external capacitors to compensate for phase margin, complex application and high cost

figure 2 The LDO in it uses capacitor multiplication technology to compensate for phase margin, but it cannot realize the function of multiple outputs

The error amplifier power supply in these two LDOs is directly provided by an external power supply, and a higher power supply voltage rejection ratio cannot be obtained.

[0003] With the rapid development of power management technology, the requirements for the dropout voltage, PSRR and cost of the low dropout linear regulator are getting higher and higher, and the traditional LDO can no longer meet the existing needs

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