Analysis and design of fully integrated very low quiescent current LDOs

Abstract

We introduce two extremely low quiescent current (I_Q) low-dropout (LDO) voltage regulators. The Low I_Q-LDO (LI_Q-LDO) has a minimum ground current of 13 μA and is designed for a maximum load current of 50 mA. The Micro I_Q-LDO (MI_Q-LDO) has a minimum ground current of 1.2 μA and is designed for a maximum load current of 5 mA. Detailed pole/zero analysis is performed to aid in the design of the LDOs. Two LHP zeros cancel the two non-dominant poles which extend the bandwidth and improve transient response. Both designs are fully integrated, stabilized with an on-chip capacitive load of 100 pF. A process-independent figure of merit (FOM) is proposed to compare LI_Q-LDO and MI_Q-LDO with other published work.