High Frequency Buck Converter Design Using Time-Based Control Techniques

Seong Joong Kim, Qadeer Khan, Mrunmay Talegaonkar, Amr Elshazly, Arun Rao, Nathanael Griesert, Greg Winter, William McIntyre, Pavan Kumar Hanumolu

Research output: Contribution to journalArticle

Abstract

Time-based control techniques for the design of high switching frequency buck converters are presented. Using time as the processing variable, the proposed controller operates with CMOS-level digital-like signals but without adding any quantization error. A ring oscillator is used as an integrator in place of conventional opamp-RC or Gm-C integrators while a delay line is used to perform voltage to time conversion and to sum time signals. A simple flip-flop generates pulse-width modulated signal from the time-based output of the controller. Hence time-based control eliminates the need for wide bandwidth error amplifier, pulse-width modulator (PWM) in analog controllers or high resolution analog-to-digital converter (ADC) and digital PWM in digital controllers. As a result, it can be implemented in small area and with minimal power. Fabricated in a 180 nm CMOS process, the prototype buck converter occupies an active area of 0.24 mm2, of which the controller occupies only 0.0375 mm2. It operates over a wide range of switching frequencies (10-25 MHz) and regulates output to any desired voltage in the range of 0.6 V to 1.5 V with 1.8 V input voltage. With a 500 mA step in the load current, the settling time is less than 3.5 μs and the measured reference tracking bandwidth is about 1 MHz. Better than 94% peak efficiency is achieved while consuming a quiescent current of only 2 μ A/MHz.

Original languageEnglish (US)
Article number6998097
Pages (from-to)990-1001
Number of pages12
JournalIEEE Journal of Solid-State Circuits
Volume50
Issue number4
DOIs
StatePublished - Apr 1 2015

Keywords

  • Buck
  • PID controller
  • VCO-based integrator
  • dc-dc converter
  • high efficiency
  • high switching frequency
  • ring oscillator integrator
  • time-based
  • voltage controlled oscillator

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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  • Cite this

    Kim, S. J., Khan, Q., Talegaonkar, M., Elshazly, A., Rao, A., Griesert, N., Winter, G., McIntyre, W., & Hanumolu, P. K. (2015). High Frequency Buck Converter Design Using Time-Based Control Techniques. IEEE Journal of Solid-State Circuits, 50(4), 990-1001. [6998097]. https://doi.org/10.1109/JSSC.2014.2378216