A LDO Regulator With Weighted Current Feedback Technique for 0.47 nF–10 nF Capacitive Load Xiao Liang Tan, Student Member , IEEE, Sau

Abstract

A Weighted Current Feedback (WCF) technique for output capacitorless low-dropout (OCL-LDO) regulator is pre- sented in this paper. Through fee dback of a weighted current, the WCF permits smart management of the output impedance as well as the gain from the inter-gain stage. Based on th e Routh–Hurwitz stability criterion, the WCF can avoid the right-half plane (RHP) pole and push the left-half plane (LHP) non-dominant complex pole pair to a higher frequency. Besides, it p rovides good regu- lator loop gain and fast transient response. Validated by UMC 65 nm CMOS process, the simulation and measurement results have shown that the WCF LDO regulator can op erate at a load capacitance ( ) range from 470 pF to 10 nF with only 3.8 pF compensation capacitor. At a supply of 0.75 V and a quiescent current of 15.9 µA, the proposed circ uit can support a maximum load current of 50 mA. When switches from 0 to 50 mA in 100 ns, the output can settle within 400 ns for the whole range. For a case of single capacit or ( 470 pF), the settling time is only 250 ns. The comparison results have shown that the W C FL D Or e g u l a t o ro f f e r sac o m p a r a b l eo rb e t t e rt r a n s i e n t figure-of-merit (FOM) and ad ditional merit to drive wide load capacitance range.