Frequency compensation scheme for LDO regulator to drive large current loads

Abstract

The invention belongs to the field of analog integrated circuits, and specifically provides a frequency compensation scheme for an LDO regulator to drive large current loads. In the scheme, two-stage operational amplifiers having approximate monopole points, a buffer stage and an output stage. Capacitor compensation is introduced innovatively, so that a two-stage error amplifier originally having two low frequency pole points becomes an approximate monopole point system, and the position of the pole point can be manually controlled. According to the scheme, the pole point is set as a secondary pole point high in frequency, and after an output capacitance and parasitic resistor (ESR) is introduced in a parasitic zero point, the pole point is appropriately compensated. The output pole points changing with loads are still main pole points, and by reasonably selecting filtering capacitance of an output end, the generated zero point is located at the maximum loop gain GBW frequency. The inside parasitic zero point is located at high frequency due to the specific circuit structure. Finally, the whole low-pressure-difference linear voltage stabilizer achieves frequency stability in the full current load change range, and the phase margin is more than 50 degrees.

Description

technical field [0001] The invention relates to the field of power management, in particular to a frequency compensation scheme for an LDO regulator driving a large current load. Background technique [0002] In recent years, due to the wide use of various electronic products, the power management system as a power supply is essential, and the power management part is very important for the normal use of the product. At present, there are two types of mainstream regulators: linear regulators and switching regulators, and specific applications often require a compromise. Compared with the switching power supply, the LDO (Low Dropout Linear Regulator) has lower output voltage noise and ripple, and the circuit structure is simpler and requires fewer peripheral devices, so the LDO is still a cost-effective s Choice. [0003] In the design process of LDO, a good frequency response is a prerequisite for the stable operation of the regulator. However, in some systems that drive ...

AI Technical Summary

Problems solved by technology

However, in some systems that drive large current loads, due to the very large range of load impedance changes (several ohms to thousands of ohms), the output pole and power tube gain change drastically, and system oscillation may occur, resulting in frequency stability problems

Traditional Miller compensation cannot effectively deal with such a large range of variation

Images