A Fast Transient Response Fully Integrated LDO With a Novel Resetting Oscillator Control Method

This article introduces a novel resetting oscillator regulator (ROR) control method for low-dropout (LDO) regulators, designed to achieve fast settling times for both load and reference input steps. The proposed ROR integrates a high-speed loop that independently functions as an oscillator in a closed-loop configuration, along with a separate high-rate resetting oscillator. The resetting oscillator reinitializes the internal nodes of the ROR loop, preventing oscillations and enabling the system to function as a high-speed regulator. Compared to prior works, the proposed ROR demonstrates improved load and reference step response speeds while maintaining a simple implementation. Fabricated using a 0.18- $\boldsymbol {\mu }$ m CMOS process, the ROR achieves fast settling times of 15 ns for low-to-high and high-to-low reference steps. It also demonstrates settling times of $25\sim 30$ ns for a 400-mA load step, utilizing an integrated 50-pF output capacitor. The ROR consumes only $130~\boldsymbol {\mu }$ A of quiescent current and supports a maximum output current capability of 500 mA. The input and output voltage ranges of the proposed ROR are $1.5\sim 1.8$ V and $0.9\sim 1.6$ V, respectively. In addition, the regulator exhibits a low output ripple of $0.3~\mathbf {mV}_{\text {rms}}$ , occupies a compact active area of only $0.08~\mathbf {mm}^{2}$ and achieves a low 3.2-fs figure of merit (FOM $\mathbf {_{T}}$ ).