An Asynchronous Geometric Sequence Array-Based Binary Search Digital Low-Dropout Regulator for $O$(log$n$)-Complexity Coarse Searching Operations
Hyunjin Kim, Taehyeong Park, Seokjin Kim, Seokhee Han, Mingi Jeong, Jaekyun Kim, Inho Park, Chulwoo Kim · IEEE Transactions on Power Electronics · 2024
This article presents a coarse search scheme for digital low-dropout regulators (DLDOs) that enables an$O$(log$n$)-complexity of coarse searching operations. To address the effectiveness of the searching algorithm, the proposed DLDO conducts asynchronous coarse searching using the proposed binary search scheme and synchronous fine searching using a fixed-precision linear searching scheme. The chip was fabricated using a 28-nm process, and the proposed DLDO was designed to cover an output voltage ($V_{\text{OUT}}$) of 0.45–0.95 V with an input voltage ($V_{\text{IN}}$) of 0.5–1 V. The proposed DLDO regulates the output with a wide load range from 15$\Omega$to 450 k$\Omega$at$V_{\text{OUT}}$= 0.45 V and$V_{\text{IN}}$= 0.5 V condition. Compared with the conventional binary search scheme, the proposed DLDO achieves an average coarse searching time improvement of 3.7$\mu$s for light-to-heavy load-transition and 32$\mu$s for heavy-to-light load-transition.