无片外电容LDO的补偿方法研究

Research on Compensation Method of off-Chip Capacitor-less LDO

无片外电容LDO器件无法通过片外电容提供频率补偿和瞬态稳压,为了弥补由此带来的器件在稳定性和瞬态特性上的缺陷,需要额外设计补偿电路。研究选用普通源极跟随器作为一种结构简单的缓冲器,作为补偿手段,以提高无片外电容LDO的功能表现。补偿电路通过SMIC 0.18μm CMOS工艺实现,基于对普通源极跟随器的特性的理论分析,进一步设计出超级源极跟随器。通过理论分析与电路仿真,综合研究了无缓冲器、普通源极跟随器、超级源极跟随器三种情况对LDO特性的影响。

The off-chip capacitor-less LDO devices cannot provide frequency compensation and transient voltage stabilization through off-chip capacitors.Additional compensation circuits need to be designed to make up for the defects in stability and transient characteristics of devices caused by that.In order to improve the performance of off-chip capacitor-less LDO,the common source follower is chosen as a simple buffer and compensation means.The compensation circuit is realized by SMIC 0.18μm CMOS process.Based on the theoretical analysis of the characteristics of common source follower,a super source follower is further designed.Through theoretical analysis and circuit simulation,the effects of three situations,namely no buffer,common source follower and super source follower,on the characteristics of LDO are studied comprehensively.