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Highly-efficient Low-Noise Buck Converters for Low-Power Microcontrollers

Ahmed, Muhammad Swilam Abdelhaleem
http://orcid.org/0000-0003-3998-0598
http://rave.ohiolink.edu/etdc/view?acc_num=osu1542277717997166

Abstract Details

2018, Doctor of Philosophy, Ohio State University, Electrical and Computer Engineering.
Microcontroller Units (MCUs) are central and essential to many consumer electronic and industrial applications, including communication systems, automotive, and Internet of Things (IoT). Since, these MCUs can be used in various applications with different operating conditions, designing the internal power supply of such MCUs is quite challenging. For example, in some applications the MCUs could be powered from a Li-ion battery while in other application it could be powered from on-board regulator, or even an AC-to-DC adapter. This indeed requires the internal power supply of such MCUs to handle a very wide range of input voltages. In addition, these MCUs typically contains analog and digital circuits that operates from different supply levels. As a result, the internal power supply of the MCU has also to support a wide range of output voltage instead of designing separate power supply for each block which requires additional design and layout efforts. Moreover, depending on the performance requirements of the MCU or the mode of operation, the current consumption can vary very widely. It can be as high as 150-300 mA in active and high performance mode or it can be as low as 10-200 µA in sleep or idle mode. Consequently, the internal power supply of the MCU has to support a wide range of load currents. It is important to mention that since MCUs usually stay more than 50% of their time in sleep mode, the efficiency of their internal power has to be high not only in active mode (heavy load condition), but also in sleep mode (ultra-light load condition). Furthermore, each application puts different limitations and constrains on the passives (i.e. inductors or capacitors) used with the MCU. This includes different size and cost which exaggerate the constrains of the MCU’s internal power supply which has to support a very wide range of passive components as well. Most importantly, since some low-noise MCUs usually contain noise sensitive IPs such as PLLs, Oscillators, and ADCs, the noise performance of the MCU’s internal power supply is of a big concern. All these aforementioned factors put a lot of constrains of the MCU’s internal power supply. Among all differnet options for implementing this power supply, buck regulator is considered a very attractive choice because of its fundamental high power conversion efficiency. However, implementing a buck regulator that is able to handle a wide range of input and ouput voltages, as well as a wide range of passives without re-customization or re-optimization of its parameters is quite challenging. In addition, the switching noise associated with buck regulators makes them very hard to be integrated within low-noise MCUs. In this research work various circuit and system techniques are proposed to solve all the above mentioned challenges and constrains of the MCU’s buck regulator. A delay-based hysteretic controller is proposed to achieve high efficiency across a wide range of load current, input/output voltages, and passive components while minimizing the switching frequency variations with the input and output voltages compared to conventional hysteretic controller without any adaptation circuit or digital frequency correction loops. Furthermore, a universal low noise (spur-free) technique is proposed to mitigate the switching noise problem of buck regulator used to direct power a 14-bit ADC and proves to be very effective in not degrading the performance of the ADC at all.
Ayman Fayed (Advisor)
Patrick Roblin (Committee Member)
Steven Bibyk (Committee Member)
105 p.
Electrical Engineering
DC-DC Power Regulator, Buck Regulator, Microcontrollers, Hysteretic Control, Adaptive on-Time Controller, CCM, DCM, Delay-based Hysteretic Controller, Power Management, Switching Regulator, Spur-free, Low noise Switching, Emulated Ripple Control

Recommended Citations

Citations

  • Ahmed, M. S. A. (2018). Highly-efficient Low-Noise Buck Converters for Low-Power Microcontrollers [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1542277717997166

    APA Style (7th edition)

  • Ahmed, Muhammad. Highly-efficient Low-Noise Buck Converters for Low-Power Microcontrollers. 2018. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1542277717997166.

    MLA Style (8th edition)

  • Ahmed, Muhammad. "Highly-efficient Low-Noise Buck Converters for Low-Power Microcontrollers." Doctoral dissertation, Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1542277717997166

    Chicago Manual of Style (17th edition)

osu1542277717997166
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This open access ETD is published by The Ohio State University and OhioLINK.