Based On The Double Loop Compensation Of High-load And Low-power Research And Design Of LDO Linear Regulators

With the rapid development of electronic technology,electronic products to be popular,especially the development of portable electronic products more quickly,which makes efficient power management program is more and more important.Low Dropout Regulator(LDO)is one of the most competitive power solutions because of its simple circuit,low cost,low noise,fast response,high power supply rejection ratio and low power consumption.So the design of high-performance indicators LDO chip is to adapt to the power market is an inevitable requirement.At the same time the integration of the IC industry is also getting higher and higher,the functional integration of a variety of portable devices are also increased,usually a small device can integrated a few devices function,and the function is more perfect than before,and the problem of multi-functional equipment is the need for more and more power,and provide high current is one of the important means to improve the power,so the study and design of high-load linear regulator has important significance.LDO maximum output current parameters are limited by the size of the regulator tube,so at the reason of the high load,the size of the power tube will be relatively large,parasitic capacitance will increase,making the system frequency compensation becomes difficult,and the larger output current range also increases the difficulty of frequency compensation.This paper first introduces the basic working principle of LDO,gives the definition of LDO index and the relationship between each index;then it introduces the stability of LDO and the commonly used frequency compensation technology,combining with the design goal,the core modules of LDO are designed by using the frequency compensation technique of double loop compensation which is suit for high load;the function modules of LDO are also designed,analysis the working principle and the corresponding requirements of these modules.The requirements of Virtuso provided by Cadence Software to achieve the circuit to build,and through the spectre software to complete the simulation of the various functional modules;integrated two can work independently of the LDO,two output with discrete power and independent enable function,can effectively reduce the system static Power consumption.Based on the design of the module such as bandgap reference,LDO core module,Powergood module,UVLO module,reset and reset delay module,temperature protection circuit and overcurrent limit circuit,the whole of LDO is completed based on Hua Hong 0.35μm BCD process Circuit design.The overall circuit is simulated using the Cadence Specter tool.The operating voltage of the circuit is 2.7V ~ 5.5V,the output voltage is 3.3V and 1.2V respectively,the maximum output load current is 1A and 2A,the low frequency gain is more than 70 d B,the phase margin is 50 degrees,the power supply rejection ratio(PSRR)60d B or more,the double-loop compensated frequency compensation method effectively solves the problem of system stability caused by large load current,and achieves the expected design goal.Finally complete the layout design,after simulation verification,streaming,packaging,testing work.