A Wide Input Range Digitally Powered Capless LDO

Abstract

The invention belongs to the technical field of integrated circuits, and in particular relates to a digital power supply Capless LDO with a wide input range. The circuit of the present invention includes an input stage with increased gain and slew rate, a push-pull Buffer stage, and a power stage with a slew rate enhancement effect, and the first-stage operational amplifier of the present invention is designed to increase the slew rate and increase the transconductance ; The second stage push-pull drives the power tube, which can optimize the overshoot and drop-off of the LDO output voltage; the third stage separates the power tube to optimize the transient response. When the LDO is light-loaded or no-loaded, the outermost large power tube is not turned on, and the internal loop constitutes a traditional LDO feedback loop to clamp the output voltage. When the load is heavy, the output high-power tube is turned on, which can respond quickly and provide suitable power supply voltage.

Description

Technical field [0001] The present invention belongs to the field of integrated circuit technology, specifically relates to a wide input range of digital power supply Capless LDO. Background [0002] LDO (Low Drop Out Linear Voltage Regulators), also known as low dropout linear regulators, are widely used in various IC chips to power different functional modules. According to whether the output of the LDO needs to be connected to the large capacitor on the PCB by wire outside the chip, the LDO is simply divided into off-chip large capacitance LDO and Capless (no off-chip large capacitance) LDO. Structures such as external large-capacitor LDOs Figure 1 As shown, due to the use of large capacitors at the power supply end, it will increase production costs: 1, it is necessary to increase the PAD pin on the top metal of chip manufacturing, which increases the area cost of the chip. 2. Capacitor components need to be introduced on the PCB board to increase cost. [0003] In some LDO...

AI Technical Summary

Problems solved by technology

The structure of the external large capacitor LDO is as follows: figure 1 As shown, because the power supply end uses a large capacitor, it will increase the production cost: 1. It is necessary to add PAD pins on the top metal of the chip manufacturing, which increases the area cost of the chip

2. It is necessary to introduce capacitive components on the PCB board, which increases the cost

Although Capless LDO has the advantage of saving cost, it brings challenges to circuit designers: because it needs to achieve loop stability and small overshoot (Over Shoot) under light and heavy loads without large off-chip capacitors. ), undershoot (Under Shoot), which requires the designer to specially design stability and high bandwidth for the compensation of the circuit, and at the same time need to use some enhanced transient technology to improve the transient response and reduce the power supply caused by load switching Unstable voltage

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