Design Of Low Drop-Out Regulator With Low Voltage

With the developments of electronics and telecommunication,portable electronical products become more and more popular.The developments of power management technologies and applications are rapidly promoted.A high-accuracy,micro power and low-dropout(LDO)voltage regulator is presented in this paper.A novel compensation structure that using the Active-Feedback Frequency Compensation (AFFC)scheme and the Cascode Miller Compensation scheme is presented,which to solve the stability problem of low dropout voltage regulators.Compared with the conventional methods,it keeps the bandwidth stable to improve the performance of transient response greatly.The new LDO effectively overcomes the stability problem,facilitates the use of a ceramic capacitor.The LDO voltage regulator's system increases the open loop gain by 30dB by using the structure of three stage amplifiers,which makes the LDO have high line regulation and load regulation specification.The new LDO was operable at input voltage 1.7V.A novel band-gap reference structure is presented,which has the bias current of OP AMP that generated by the band-gap voltage reference self,thus having the PTAT current generator omitted,reducing the chip area and making the reference current closer to the ideal PTAT current.Simulation result show that the band-gap voltage regulator temperature coefficient is 12ppm/℃within the temperature range:-20℃～120℃,the power rejection at low frequency is 75dB,and the quiescent current of this band-gap voltage reference is about 12uA.The function of preventing temperature and current from over ranging is designed in the regulator.