Research And Design Of A Capacitor-less Low Dropout Regulator

With the rise of technologies such as artificial intelligence,5G devices,the internet of things and new energy,the performance improvement of power management chip is widely concerned.In power management chips,LDO is widely used for its simple structure,stable output voltage small ripple and other characteristics,and tends to integrate into system-on-chip(SOC).Because there is no need for off-chip capacitors or connecting small capacitors to save area,the research of the capacitors-less LDO has become a current hot research direction.The working principle of the LDO with off-chip capacitor was detailed,and the role played by the off-chip capacitor was discussed.The working principle and characteristics of the LDO with off-chip capacitor were compared with the capacitors-less LDO;Several known structures and techniques for solving the stability and transient characteristics of the capacitors-less LDO were briefly described.The working principle of the designed capacitors-less LDO was described,and the working principle and simulation results of the main modules were analyzed.The design mainly adopted the topology structure of the NMOS transistor as the power transistor,which can achieve stability with no need for off-chip capacitors or connecting small capacitors,and realize the adjustable output voltage with the output voltage range of 1.2V ~ 5V.The layout of the chip circuit was optimized,and then the layout was simulated,and the parameters were analyzed;The chip was tested and verified,and the results were analyzed in depth.The chip was designed based on the 0.18?m BCD process.The cadence Spectre tool was used to perform DC,AC and transient simulation analysis on the design circuit.The simulation shows that when the input voltage range is set within 1.7V ~ 5.5V,the output voltage range can achieve a stable output voltage of 1.5V ~ 5V by setting the resistance of the feedback resistor;The typical value of the dropout voltage is about 75 mV,and the maximum value in the whole range does not exceed 200 m V;The precise value of the linear adjustment rate can reach less than0.01%;In the range of load current 1mA ~ 400 mA,the precise value of load regulation is less than 0.002%.In the range of load current 10 mA ~ 400 mA,the precise value of load regulation is less than 0.0005%.In the temperature range of-55?~125?,the output can be stable.