| The miniaturization of dc--dc switch-mode power supplies (SMPS) is of a key importance in volume-sensitive portable devices, such as cell phones, tablet computers, and digital cameras. In these systems, multiple SMPS are required to provide well regulated voltage and power to various electronic components such as the central processing unit (CPU) and random-access memory (RAM). The combined volume, weight, and surface area footprint of these SMPS is usually the largest component.;Traditionally, SMPS volume reduction has been achieved through increased switching frequencies; however, for power-sensitive applications this is undesirable due to the increased switching losses. This thesis presents two alternative, power-efficient, SMPS miniaturization methods: one control and one topology based.;The presented controller recovers from load transients with virtually minimum possible output voltage deviation, reducing the reactive component size. The controller utilizes a simple algorithm, requiring no knowledge of the converter parameters and virtually no processing power. The simplicity of the control concept enabled the design of an area and power efficient integrated circuit (IC) implementation.;The entire IC is implemented in a CMOS 0.18mum process on a 0.26 mm 2 silicon area, which is comparable to the state-of-the-art analog solutions. For the experimental system the deviation (output capacitor size) is about four times smaller than that of a fast PID compensator having a 1/10 th of the switching frequency bandwidth.;The second solution is a complementary converter topology that has a smaller output filter volume, improved dynamic response, and lower switching losses compared to the state-of-the-art solutions. To reduce the volume and switching losses, the input-to-output voltage difference is decreased with a capacitive attenuator that replaces the input filter capacitor and has approximately the same volume. Both the attenuator and the downstream buck converter share the same set of switches, minimizing conduction losses. A single multi-mode digital controller governs operation of both stages, seamlessly regulating the output and input center-tap voltages. Experiments with a 5--1.5-V, 2.5-A, 1-MHz prototype show that, compared to the conventional buck, the merged topology has 43% smaller inductor, 36% smaller output capacitor, up to 30% lower power losses, and a 25% faster transient response. |
