The Design And Study Of High Stability LDO Based On Dynamic Compensation

Compared with other power IC, Low-dropout linear regulator(LDO) owns highefficiency,low noise,high ripple rejection, and it is widely used in automotiveelectronics, portable electronics, electronic communication equipments, governmentalindustrials and medical equipments.So there is a great significance to carry out theresearch of this paper.In allusion to the demand to electrical source drive CMOS chip, which is theAMOLED display of intelligent mobile phone and tablet computer, This passage isbased on the0.13micron BCDv8technology from ST microeletronics company.Having designed an LDO linear regulator, it has several following characteristics: itsoutput voltage is in high accuracy, well line regulation and load regulation, adjustablewide and high voltage (the range of the voltage is10V~16V output to6V~12V). and theelectrical source is restrained well. This paper mainly focuses on the system stability ofthe LDO linear regulator, and its frequency compensation techniques. After analyzingall kinds of factors ensteady from the LDO linear regulator in deep, the author analyzesthe advantages and disadvantages of different frequency compensation methods, andputs forwad the system architecture of the LDO linear regulator. The system includesdynamic zero compensation units, transconductance enhancement units, super sourcefollower and dynamic gain compensation units. the function and the design indexes ofeach module are determinate. This system solves the problem of stability of ordinaryLDO regulators in different environments. Based on this we have finished the design ofeach module and the system structures of the circuit, and the simulation of the circuitstructures. In the whole working conditions, the low-frequency gains55dB upward, thephase margin achieves40degrees upward, the voltage error decreases±0.6%hereinafter, and the low-frequency PSRR achieves-40dB upward. The results show thatthis frequency compensation method is new and practical, and it solves the change ofthe laden current, the change of the input and the output voltage and the stability of theLDO linear regulator effectively. By this the stability of the LDO linear regulatoraffected by the external environment reduces greatly, we achieve the expectant designgoals.