Design Of LDO Based On Voltage Controlled Current Source Compensation

With the development of science and technology,more and more electronic products have emerged in people's lives,which have brought convenience to people and greatly improved people's living standards.At the same time consumers expect higher and higher expectations of electronic products,small size,easy to carry,endurance,security and other performance requirements are more demanding.It is an important safeguard to ensure the normal operation of electronic equipment.In the continuous efforts of designers,higher performance,low power consumption,small size,with a strong load capacity of the power chip is designed.Now two power management chips with the highest market share are DC-DC converter and LDO.These two power supply chips are widely used.All kinds of portable devices have their shadow.Based on the introduction of two kinds of power chip their principle,advantages and disadvantages,the load capacity and the differences in the specific application at the same time,clarifies the important position of LDO chip in power chips and future research directions.Due to the poor stability of the LDO loop,each LDO circuit needs an additional frequency compensation circuit to enhance the stability.There are two kinds of traditional compensation methods,ESR compensation and Miller compensation.This paper summarizes the advantages and disadvantages of the two compensation methods by analyzing its transfer function,zero pole position and whether the compensation position is accurate,whether it needs large on-chip capacitance compensation and so on.These two kinds of traditional compensation methods are easy to realize,and they have played an important role in the early application,but it has its own shortcomings.Therefore,this design uses a new type of compensation-voltage controlled current source compensation.The voltage controlled current source module in the compensation mode is composed of a transconductance enhanced amplifier,an on-chip capacitor(0.9p F)and a current mirror.The purpose of the transconductance amplifier is to put the extra poles of the module to the outside of the bandwidth.The current mirror and the on-chip capacitor together determine the zero position.In this paper,the compensation principle of the voltage-controlled current source compensation method is introduced in detail,and it is verified that the voltage-controlled current source module accurately compensates the correctness of a zero point in the loop without introducing additional poles.In this paper,a voltage controlled current source is used as the frequency compensation circuit LDO.Phase margin of the design of the LDO in the load range(30m A-300?A)greater than 45°.The PSRR value is above 70 d B,the static power consumption is 112 A,and the area is about 220 x 150 um2.With a small on-chip capacitance,low static power consumption,frequency compensation and stability advantages.