An Output-Capacitor-Free NMOS Digital LDO Using Gate Driving Strength Modulation and Droop Detector

Jaejin Kim, Gunmo Koo, Seongmin Lee, Jae Hoon Shim, Kunhee Cho

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

An output-capacitor-free NMOS digital LDO (DLDO) using gate driving strength modulation (GDSM) is described. The proposed DLDO is mainly based on the time-driven topology while the GDSM changes the gate driving level adaptively according to the load current condition. The proposed GDSM lowers the gate driving level in the light load condition which improves the load transient response, widens the load current dynamic range, and reduces the output voltage ripple. A droop detector combined with the modulation scheme is also proposed to further improve the undershoot and recovery time. The proposed DLDO has been implemented in 28 nm CMOS and the 20, 000× load range is obtained even with 256 unity power switch arrays. When the load current changes from 5 mA to 85 mA, the VOUT droop and recovery time are 130 mV and 2.5 μs, which are 4.92× and 70× improvements compared to the baseline time-driven DLDO, respectively.

Original languageEnglish
Pages (from-to)4975-4985
Number of pages11
JournalIEEE Transactions on Circuits and Systems I: Regular Papers
Volume70
Issue number12
DOIs
StatePublished - 1 Dec 2023

Keywords

  • Digital LDO
  • droop detector
  • dynamic voltage scaling
  • gate driving strength modulation
  • wide load dynamic range

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