| In low-power portable applications, there are a lot of power domains. Different power domains require DC-DC converters to generate tightly regulated supply voltages from the available battery voltage. In such applications, efficiency, volume and footprint area occupied by a DC-DC converter are very important.; To reduce the area, possible approaches include (1) monolithic integration, (2) reduction of the external component size, and (3) use of alternative converter topologies. In the thesis, we examine the approaches (1)-(3) with respect to a typical application example having the following specifications: the supply voltage is 2.0 V, the output voltage is 1.0 V, and the load current is up to 200 mA. In addition to the exploration of techniques leading to a small size, we investigate feasibility of digital controller implementations at relatively high switching frequencies.; At first, the approaches (1) and (2) are examined assuming a standard synchronous buck converter. Intuitively, if the power switch is large, the conduction loss decreases but the switching loss increases, and vice versa. So an optimization method of the power-stage is examined, and then we present design of a complete digitally controlled monolithic buck converter operating at 10 MHz switching frequency.; To decrease the inductance further, the approach (3) is examined: a 3-level synchronous buck converter is applied. We present an optimization method of the power-stage, derivation of the small-signal models, and design of a complete digitally controlled monolithic 3-level buck converter. The converter operates with a very small filter inductance at 10 MHz switching frequency. |
