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Systematic design procedure for buck DC-DC converters


In today's market, switching power converters are widely used in many applications. The low power DC-DC converters are used in many battery-operated portable electronic devices such as cellular phones, personal digital assistants (PDAs), and other devices. Small size and high efficiency are the key requirement for on-chip integrated DC-DC switched mode power converters  used in low power portable applications. The high power DC-DC converters are used extensively in automotive industry. In vehicles, the battery is used to supply all electronic devices in the vehicle such as sensors, electronic control unit (ECU), and car communication networks which require stable low voltage supply to work properly. During engine starting, the battery voltage can easily swing between 4 V and 40 V. Thus, power converters are used to supply the low voltage electronic devices and sustain the supplied voltage constant regardless the variation in the battery voltage.

The power converters can be classified into four main categories: DC-DC converters, AC-DC rectifiers, DC-AC inverters, and AC-AC converters. In the DC-DC converters, the well-known topologies are buck converter (step-down), boost converter (step-up), and buck-boost converter (step-down or step-up).      


In this study, the synchronous buck DC-DC converter is investigated. The conventional control topologies such as voltage mode and current mode control are explored. A systematic design procedure for the system level and circuit level is to be developed. New techniques to ameliorate the efficiency and mitigate the substrate leakage current are to be investigated.


The plan for this internship can be divided into four stages: 

  1. Understand the DC-DC converter basic concept and control theory
  2. Develop a systematic procedure for the system level of DC-DC converter

    • Extend an existing MATLAB model for voltage mode control to comprise the circuit nonidealities.
    • Accurate efficiency calculations.
    • Develop the same systematic procedure for the current mode controller.

  3. Circuit design based on the system level
  4. Research problems 

    • Efficiency amelioration techniques. 
    • Techniques to mitigate the substrate minority currents during the dead-time.


  • Concepts of Analog/Digital circuit design. 
  • Concepts of MATLAB (M-files and simulink).
  • Concepts of Cadence Virtuoso Analog environment.



  • B. Murari, F. Bertotti, and G.Vignola, "Smart Power ICs," 2nd ed. Berlin, Germany: Springer-Verlag, 2002, pp. 218-220.
  • R. Erickson, and D. Maksimovic. "Fundamentals of power electronics," Springer, 2001.
  • Y. Moursy et al., "AUTOMICS: A novel approach for substrate modeling",18th IEEE European Test Symposium, May, 2013.
  • C. Lee, and Philip KT Mok , "A monolithic current-mode CMOS DC-DC converter with on-chip current-sensing technique", Solid-State Circuits, IEEE Journal of 39.1 (2004): 3-14.
  • A. Parayandeh et al. "A 10 MHz mixed-signal CPM controlled DC-DC converter IC with novel gate swing circuit and instantaneous efficiency optimization", Energy Conversion Congress and Exposition (ECCE), 2011 IEEE. 


This work is in the context of the European FP7 AUTOMICS project. The Consortium includes many industrial  partners like Valeo, Austria micro-system AMS, ST-Italy, Continental, and AdMOS.