A LDO REGULATOR WITH PRE-REGULATOR AND MULTI-ZERO AND MULTI-POLE FREQUENCY COMPENSATION

摘要

A low dropout (LDO) linear regulator with pre-regulator is presented in this paper. The LDO is suitable for wide power supply of 4.5-28 V for smart battery system applications to generate a stable 1.8 V output. The proposed LDO provides high stability by pre-regulator for a rough 3.3 V as internal power supply and multi-zero and multi-pole frequency compensation. The scheme of combining of using output capacitor to set a dominant pole, utilizing a buffer stage to avoid generation of low-frequency pole, introducing an additional zero, is presented to stabilize the regulator loop for various load conditions and wide supply range. Besides, parasitic poles in high frequency can be compensated by feed-forward compensation and mirror-pole compensation.