采用增强型AB跟随器的快速响应LDO

Low Drop-Out Regulator with Fast Transient Response Based on Class AB Super Follower

设计了一种采用增强型AB跟随器作为缓冲器的快速响应LDO。利用跟随器的动态电流提高能力,显著地改善了误差放大器对功率MOS管寄生大电容的驱动;同时,由负反馈引起的阻抗降低效应将功率管的寄生电容极点推到了更高的频率,提高了环路的相位裕度。采用TSMC0.35-μm CMOS工艺进行仿真,当负载电流在0.1μs内从1mA跳变到50mA以及从50mA跳变到1mA时,相对于同等条件下的源跟随器LDO,输出峰值分别减少4mV和46mV,且稳定时间只需要0.2μs和0.5μs。

A low drop-out regulator（LDO） with fast-transient response was designed based on Class AB super follower.Dynamic current boosting capability achieved with the follower significantly improved transient response of the LDO when load was changing rapidly.Feedback of the follower lowered the output resistance and made the pole at the gate of the power transistor move to higher frequency.Simulation in TSMC 0.35-μm CMOS process showed that,when load current changed from 1 mA to 50 mA and from 50 mA to 1 mA,peak voltage of the LDO was reduced by 4 mV and 46 mV with a settling time of only 0.2 μs and 0.5 μs,respectively,compared to LDO with conventional source follower.