Ultra-low Dropout Linear Regulator With Charge Pump

With the development of artificial intelligence and the advent of the 5G era,various wearable devices,smart home products,and smart phones are emerging in an endless stream,and the speed of updating is accelerating.The battery life of electronic products is one of the important factors that determine product quality.The power management chip is a vital part.Power management chips mainly include low-dropout linear regulators and switching power supplies.Compared with switching power supplies,low-dropout linear regulators have the advantages of small area,high precision,low noise,and simpler peripheral circuits.They are power management Popular choice for chips.After studying the basic theory of LDO,this paper designs an LDO circuit with charge pump,which mainly includes charge pump,bandgap reference,error amplifier,dynamic reference,servo circuit and other circuit modules.Because the LDO circuit in this article uses an NMOS tube as the regulator tube,the voltage difference will increase to maintain the stability of the circuit.In order to solve this problem,the charge pump module is introduced into the circuit by using the voltage doubler function of the charge pump.The charge pump in this article uses the Dickson charge pump,but its structure is improved.The gate terminal and the source terminal of each MOS tube are no longer connected to form a diode.The gate signal of each MOS tube is divided into The clock shift circuit provides non-overlapping signals for it to form a switch tube,and the output voltage of the charge pump is used as the power supply voltage of the clock shift circuit,which can reduce the voltage loss of the circuit.An NPN type bandgap reference voltage source is designed.It does not use an operational amplifier.It uses the voltage characteristics of a pair of NPN tubes and a resistor divider module to achieve a temperature-independent reference voltage,and multiple voltage outputs can be obtained at the same time for other circuits.The module provides reference voltage and bias current.Modules such as over-temperature protection circuit,current-limiting foldback circuit,and current detection circuit are designed to ensure that the circuit can output a stable voltage.The LDO circuit designed in this paper is designed based on the CSMC 0.5μm CMOS process,and the Cadence software is used for simulation verification,and the simulation results meet the design specifications.The actual test result of the chip shows that when the load is 500 m A,the voltage difference of the circuit is 100 m V,the input voltage is 3.4V-5V,the output voltage is 3.3V,the power supply rejection ratio is about 66 d B when the load is 10 m A,and the linear adjustment rate is 0.03.%/V.The designed low-dropout linear regulator has good performance and can be widely used in microprocessors,portable electronic equipment and other fields.