Fast transient (FT) technique with adaptive phase margin (APM) for current mode DC-DC buck converters

Yu Huei Lee*, Shao Chang Huang, Shih Wei Wang, Ke-Horng Chen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


This paper proposes a fast transient (FT) control with the adaptive phase margin (APM) to achieve good transient response in current-mode DC-DC buck converters at different load conditions. The overshoot/undershoot voltage and the transient recovery time are effectively reduced. The APM control can always maintain the system phase margin at an adequate value under different load conditions. That is, the compensation pole-zero pair is adapted to load current to extend the system bandwidth and get an adequate phase margin. Experimental results show the overshoot/undershoot voltage is smaller than 60 mV (3%) and transient period is smaller than 12 μ s as load current suddenly changes from 100 to 500 mA, or vice versa. Compared with conventional designs without any fast transient technique, the undershoot voltage and recovery time are enhanced by 45% and 85%, respectively.

Original languageEnglish
Article number6003815
Pages (from-to)1781-1793
Number of pages13
JournalIEEE Transactions on Very Large Scale Integration (VLSI) Systems
Issue number10
StatePublished - 1 Jan 2012


  • Adaptive phase margin (APM)
  • fast transient (FT)
  • loop bandwidth
  • pole-zero cancellation
  • stability

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