| With the development of Information Technology, the portable device is becoming a mobile companion with rapidly increased functionalities, which leads to the more serious conflict between the increasing power consumption and limited battery capacity. At the same time, the portable device requires compact design and light weight to slip into a pocket. Power management in portable device demands light weight, small volume, low cost as well as long battery lifetime, which drives the development of Single-Inductor Multiple-Output (SIMO) converter. By using only one inductor, SIMO converter can generate several different regulated outputs. Due to the advantages of saving cost and reducing PCB area, SIMO converter is widely studied by both the academy and industry.In this dissertation, the topology and property of SIMO converter are studied. The SIMO converter realizes the multiple-output function at the cost of some performance degradation, including large output ripples and spikes, limited conversion range, cross regulation and reduced efficiency. Owing to the multi-loop feedback property, the SIMO converter is a more complex system than the single-output conterpart. This dissertation has built up a small signal model for SIMO converter. A system decoupling method has been proposed for system analysis and compensation design. In order to solve or suppress such existing problems, the dissertation proposes a novel fly capacitor method to reduce the output ripples and spikes; an extended pulse width modulation (EPWM) control which can automatically select step-down and step-up conversion with high efficiency; an adaptive feedback matrix method to improve the dynamic response.In this dissertation, three SIMO converters have been designed and implemented in a 0.25?m 2P4M 2.5V/5V CMOS process. (1) A single-inductor dual-output (SIDO) buck converter, which can generate two outputs of 1.2V/400mA and 1.8V/200mA with supply voltage ranging from 2.7-5V. The peak efficiency reaches 87% and the output ripples and spikes are less than 40mV. (2) A SIDO buck-boost converter, which can generate two outputs of 1-5V and 1.8-5V with supply voltage ranging from 2.5-5V. By using the proposed EPWM control, each output can be used as step down or up conversion with the peak efficiency of 90%. (3) A SIMO bipolar-output converter, which can generate two positive outputs of 1-4V and 1.8-4V and one negative output of 0?-2V with supply voltage ranging from 2.5-5V. The peak efficiency is near 90% with total power of 2.5 W. The converter can automatically select the modulation mode to improve the light load efficiency. Measurements on these three SIMO converters have verified the proposed methods. The SIMO converters are suitable for cost-effective power management of portable devices. |
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