A 10-MHz 2-800-mA 0.5-1.5-V 90% Peak Efficiency Time-Based Buck Converter with Seamless Transition between PWM/PFM Modes

Seong Joong Kim, Woo Seok Choi, Robert Pilawa-Podgurski, Pavan Kumar Hanumolu

Research output: Contribution to journalArticle


Time-based controllers are well suited for implementing both single- and multi-phase wide bandwidth high switching frequency pulsewidth modulation (PWM)-based dc-dc converters. They also consume very little quiescent current but their light load efficiency is severely degraded by switching losses. We explore pulse frequency modulation (PFM) that is commonly used to improve light load efficiency in voltage-mode controllers and extend its operation to time-based controllers. To maintain high efficiency even in the presence of dynamic load variations, we present techniques to perform automatic and seamless switching between PWM/PFM modes. Fabricated in a 65-nm CMOS, the prototype buck converter using the time-based PWM/PFM control achieves 90% peak efficiency and >80% efficiency over a load current range of 2-800 mA. Output voltage changes by less than 40 mV during PWM to PFM transitions.

Original languageEnglish (US)
Pages (from-to)814-824
Number of pages11
JournalIEEE Journal of Solid-State Circuits
Issue number3
StatePublished - Mar 2018



  • Buck converter
  • high switching frequency
  • light load efficiency
  • mode switching
  • pulse frequency modulation (PFM)
  • pulsewidth modulation (PWM)
  • time-based control

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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