Research And Design Of Low Dropout Linear Regulator Based On Dynamic Frequency Compensation

With the development of System on Chip(So C),capacitor-less low dropout linear regulator(LDO)has become a research hotspot of power management intergrted circuits(PMIC)due to its simple structure,low power consumption and low ripple.However,capacitor-less LDO has poor Loop stability and transient response under the condition of light load.Based on those,this thesis designs a LDO based on dynamic frequency compensation technique in SMIC 0.13μm CMOS process.The main contens including:Firstly,based on the analysis of the first-order bandgap voltage reference(BGR),a piecewise curvature-compensation BGR is designed by adopting piecewise temperaturecompensation and curvature-compensation technology.Simulation results show that the designed piecewise curvature-compensation BGR achieves these performances including temperature coefficient of 2.4ppm/℃ and PSRR of-95dB at low frequency.Secondly,based on the analysis of the frequency characteristics of the uncompensated capacitor-less LDO,a kind of pole-pole tracking(P-PTFC)dynamic frequency compensation LDO is designed by adopting dynamic buffer,miller compensation(MC)and active feedback frequency compensation(AFFC)technologies.Simulation results show the designed LDO achieves the loop gain of 80.4dB,the phase margin of 62.3° and the loop bandwidth of 1.3MHz with the load current of 100μA.The designed LDO achieves the loop gain of 70.5dB,the phase margin of 84.5° and the loop bandwidth of 1.2MHz with the load current of 100mA.Finally,based on the analysis and design these sub-circuits including current bias circuit,transient enhancement circuit,over-temperature protection circuit and over-current protection circuit,a ccapacitor-less LDO system with dynamic frequency compensation technique is designed in SMIC 0.13μm CMOS process.Simulation results show that the designed LDO system achieves these performances including the output voltage of 1.0V,maximum load current of 100 mA,dropout voltage of 97 mV,temperature coefficient of 3.5ppm/℃,linear regulation of 0.12mV/V and load regulation of 0.007mV/mA and PSRR reaches -62dB at low frequency.