Low Voltage Charge Pump Design For Power Management Chip

With the rapid popularity of portable products,the degree of digitization of chips is constantly improving,and the power consumption and power supply voltage are continuously decreasing.In order to meet the market demand for power management system,how to reduce area,reduce power consumption,maintain output stability,improve power efficiency is the current charge pump(CP)research and design of the hot spot.This paper based on the four-phase clock charge pump circuit suitable for low voltage conditions,the paper improves the performance of the charge pump from two aspects,one is to improve the efficiency,the other is to improve the start speed.The four-phase clock charge pump circuit designed in this paper adopts dynamic bias circuit to eliminate the influence of volume effect in the process of voltage boost.There are two innovative points in this paper.One is to use the pre-charging theory to charge the pump capacitor of each stage before the circuit starts,which increases the starting speed by 10%.Second,under the condition of low current,the four-phase clock is improved by using simple inverter and NAND gate to delay the signal,which improves the efficiency by 10%.Then the charge pump power management chip system block diagram is analyzed to determine the circuit of each sub-module.The band-gap reference voltage and comparator module are the most important,which determine the temperature and ripple characteristics of the charge pump.The bandgap reference module adopts high gain secondary operational amplifier to improve the power supply voltage rejection ratio.The comparator module in the feedback circuit adopts high voltage swing rate operational amplifier to improve the speed of the feedback loop and reduce the ripple of the system.In this paper,according to the theory of pre-charging,a four-phase clock charge pump is designed.Before starting,the charge is injected into the capacitor of each node pump.At the same time,a new four-phase clock is proposed to generate the signal,which greatly increases the efficiency and starting speed of the charge pump when the current load is low.Based on GSMC 0.13μm 1p6 M process and Cadence platform 1.5V power supply voltage,the circuit design of each sub-module of charge pump power management chip is carried out,and the output efficiency is up to 82%.The simulation results of each sub-module meet the requirements of charge pump power management system.