A 0.13-<formula formulatype="inline"><tex Notation="TeX">$\mu{\rm m}$</tex></formula> CMOS Low-Power Capacitor-Less LDO Regulator Using Bulk-Modulation Technique

Abstract

In this paper, a bulk-modulation technique is introduced for improving the performance of low-drop-out (LDO) voltage regulators. Compared to conventional LDO voltage regulators, the proposed circuit achieves improved accuracy, stability, and output load current capability. The technique is particularly suited for low-power applications such as biomedical implants and portable devices. A proof-of-concept prototype is designed and fabricated in 0.13- ${\mmb\mu}{\bf m}$ CMOS, to illustrate the enhancement that can be achieved by applying this technique. The proposed enhanced LDO regulator which is based on conventional LDO regulators is able to delivers up to 5 mA of load current while providing a 1 V ( $\sim$ 1.5% load regulation) drawing 99.0 ${\mmb\mu}{\bf A}$ from a 1.2 V supply. Measurement results confirm that as compared to conventional LDOs, the proposed circuit offers better stability as well as %75 improvement in the load current delivery and $\sim 10\times$ faster recovery time for no-load to and from full-load transitions.