Design And Implementation Of Low Power And High Transient LDO Based On On-chip Compensation

In the traditional off-chip compensation LDO(Low Dropout Regulator)circuit,its output load terminal is usually equipped with an off-chip large capacitor.This structure is not suitable for the current development demand of highly integrated,so the study of off-chip capacitor regulator is gradually becoming the mainstream.Due to the lack of off-chip capacitance at the end of output,the stability and transient response of LDO are inevitably affected.At the same time,some load circuits put forward higher requirements on the load transient response speed and power consumption design of on-chip power supply.In this paper,a low power and high transient on-chip compensation LDO circuit is designed based on SMIC 0.18 μm technology.The error amplifier in this paper combines the common gate differential input transconductance amplifier with the push-pull output stage,which can achieve a higher conversion rate at a lower static current.The coupling capacitance is embedded at both ends of the power transistor to provide AC feedback path,which can overcome the restriction of the loop bandwidth to the transient change of the load end.By introducing common-mode feedback resistance pairs to increase the dynamic current of the error amplifier in the process of transient response,the time required for the transient voltage to be restored to stability is effectively shortened,and the static current of the circuit is not affected.Through the introduction of active feedback capacitor,the phase margin of LDO is improved during no-load,and the circuit can maintain good stability in the full load range.At the same time,in order to improve the accuracy of OCL-LDO output voltage,this paper designs a band-gap reference voltage source with low temperature coefficient and a reference current source with low static current.In order to avoid damage to the chip under abnormal working conditions,overtemperature protection circuit and overcurrent protection circuit are also designed.In this paper,the OCL-LDO(output-capacitorless Low Dropout Regulator)is designed based on SMIC 0.18 μm technology.The voltage range of the power supply is 1.95～4 V,and the stable Output voltage of 1.8 V is achieved in the load range of 0.2-10 m A.The simulation results show that the maximum peak value of output voltage is less than 340 m V,the stability time is less than 2.2 μs,the static current consumption is 9.25 μA,and the power suppression ratio is 89 d B in the range of the maximum load current.