Design Of ALDO Regulator With Two-Stage Error Amplifier

In recent years, with the development of the semiconductor end products toward the thin, light, digitization and multi-functional integration, power management IC is becoming increasingly important. Due to its high stability, good reliability, low noise, good line regulation, load regulation, high power supply rejection ratio and low cost, compared with other power regulators, the low dropout linear regulator (LDO), as one commonly used power management IC, has more potential for development and can meet the development trend of in the field of electronic products. At present, most of the power management IC market share is occupied by foreign companies, so the study of power management IC has a very important significance.A LDO Regulator with two-stage error amplifier was designed in0.18μm CMOS process. The LDO Regulator is adopted two error amplifiers to improve the transient response of and applied Miller frequency compensation to improve stability of the circuit. The main amplifier which uses the standard folding cascode structure determines the main properties of the circuit. And the second stage using fast amplifier monitors the variation of the LDO output voltage. The simulation results show that the output voltage is1.8V, the temperature coefficient is10xl0-6/℃, the linear transient response is48mV when the power supply voltage is from4.5V to5.5V, the load transient response is5mV when the load current changes from0to60mA, the phase margin is74°, and the quiescent current of the entire circuit is37μA. The transient voltage of this circuit is much lower than the other previous circuits, and low-power supply is achieved.