Design And Simulation Of A High-Stability And Capacitor-Less Low Dropout Regulator

Low dropout linear regulator is wide used in various electronic devices for itssimple circuit structure, low power consumption, low noise output, higher powersupply rejection ratio, as an important part of the power management chip. Withthe rapid development of the system on chip, The capacitor-less Low dropout linearregulator is researched in low dropout linear regulator. A capacitor-less low dropoutlinear regulator is designed for system on chip in this paper with a good loop stabilityand load transient characteristics.Stability characteristics of traditional and capacitor-less low dropout linearregulator is analyzed in this article. The one-order RC compensation and polesplitting method is used to meet the stability of the system for reducing the chip areausing resistance the linear-region MOS transistor instead. The phase margin in worstcase is64.5°and in best case is83°by simulation, and it can ensure system stabilityin the entire scope of work. The power supply rejection rate of system is58.82dB atlow frequencies a56dB at1KHz Frequency in worst case.A feed-forward path is added to improve the transient response characteristics ofthe system. When the voltage increase from3V to4V within1us the maximumoutput up-overshoot is116mV and the maximum output down-overshoot is310mV.Load current increase from0to50mA within1μs, the maximum output up-overshootand down-overshoot are less than300mV. The low dropout linear regulator has awide input voltage range:2.6V-5.5V, temperature range:-40℃-150℃, can provide50mA maximum load current. The dropout in the worst case is only96mV. Quiescentcurrent is approximately57μA in the power supply voltage of3V. The over-temperature protection circuit is added to improve the overall reliability of the circuit.When the temperature rising to140℃, over-temperature protection circuit starts,with a typical hysteresis of20℃range. This entire system is designed by using the0.6μm standard CMOS technology,and use the spectre simulator of Cadence software to complete simulation work. Thesimulation results meet the design requirements.