Analysis, design, and implementation of digital dc-dc converters.
Foong, Huey Chian.
Date of Issue2013
School of Electrical and Electronic Engineering
This thesis describes the analysis, design, and realization of digitally-controlled (or digital) DC-DC converters. Digital DC-DC converters have the advantages of high signal-to-noise ratio, programmability, and portability while maintaining high efficiency. The digital DC-DC converters are targeted for the power management IC for power-critical devices such as portable devices, energy harvesting applications and wireless sensor networks. This thesis also presents an integrated digital DC-DC converter with a supply- and process-insensitive hybrid-segmented 12-bit DPWM, a predictive and feedforward controller, and a window SAR ADC to achieve fast transient response and low overshoot. An additional predictive or jerk component is introduced to the conventional PID controller to speed up the transient response and reduce the settling time by 50%. In addition, a feedforward control is also employed to further improve the transient by evaluating the change in the inductor current during the on and off time of the power transistors. The proposed design is verified on silicon in CMOS 0.18 μm process. The digital DC-DC converter achieved a settling time of 4 μs and an overshoot of 15 mV for a step-load transient of 450 mA, which are improved significantly as compared to the prior arts.