A CMOS Low Dropout Regulator with Extended Stable Region for the Effective Series Resistance of the Output Capacitor

Hsuan-I PAN  Chern-Lin CHEN  

IEICE TRANSACTIONS on Electronics   Vol.E91-C    No.8    pp.1356-1364
Publication Date: 2008/08/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e91-c.8.1356
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Electronic Circuits
CMOS analog integrated circuits,  stability,  compensation,  low-dropout regulator,  

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In this paper, a new compensation scheme and a corresponding pass element structure for a CMOS low-dropout regulator (LDO) are presented. The proposed approach effectively alleviates the strict stability constraint on the ESR of the output capacitor. Stability of a CMOS LDO with the conventional compensation requires the effective series resistance (ESR) of the output capacitor in a tunnel-like region. With the proposed design approach, an LDO can be stable using an output capacitor without ESR. A 2.5 V/150 mA LDO has been implemented using a 0.5-µm 1P2M CMOS process. The experimental results illustrate that the proposed LDO is stable with an output capacitor of 0.33 µF and no ESR.