一种快速启动的电容式电荷泵设计

Design of a Fast-Start Capacitive Charge Pump

针对电荷泵在输出负载电容大的情况下启动速度慢、容易增加噪声和系统功耗的问题,设计一种快速启动的电容式电荷泵电路。该电路包括主电荷泵、逻辑控制电路、辅助电荷泵、稳压电路和升压电路。其中,逻辑控制电路根据主电荷泵的输出控制辅助电荷泵的开闭,辅助电荷泵根据逻辑控制电路的控制信息控制升压电路的开闭,借助稳压电路减少主/辅电荷泵的输出纹波,稳定输出电压,最终由升压电路实现输出端电压升高。该电路还可做到在第一使能信号到来时,通过逻辑电路和辅助电荷泵控制NMOS器件的通断,使电荷泵第一输出端电压迅速上升到电源电压VCC,而没有NMOS器件传递高电压阈值损失的问题,极大缩短输出负载电容达到稳定值的时间,达到快速启动的目的。

In order to solve the problems that the charge pump starts slowly and easily increases noise and system power consumption when the output load capacitance is large, a capacitor charge pump circuit with fast start-up is designed. The circuit includes a main charge pump, a logic control circuit, an auxiliary charge pump, a voltage stabilizing circuit and a boosting circuit. The logic control circuit controls the opening and closing of the auxiliary charge pump according to the output of the main charge pump, and the auxiliary charge pump controls the opening and closing of the booster circuit according to the control information of the logic control circuit. The output ripple of the main/auxiliary charge pump is reduced by means of the voltage stabilizing circuit, and the output voltage is stabilized. The design can control the on-off of NMOS devices by logic circuit and auxiliary charge pump when the first enable signal comes, so that the voltage of the first output terminal of the charge pump quickly rises to the power supply voltage VCC, without the problem of high voltage threshold loss of NMOS devices, which can greatly shorten the time for the output load capacitance to reach a stable value and achieve the purpose of fast start.