| Summary: | 碩士 === 國立臺灣大學 === 電子工程學研究所 === 93 === Abstract
Due to rapid development of CMOS technologies, more and more transistors can be fabricated on a single chip. Since these large digital circuits such as the processors and ASICs need the large power consumption, the complicated power control technique must be adopted to reduce power consumption. There is a large current step in the voltage supply sources of ASICs and processors because of frequently switching from the sleep mode to the hot-run mode. Consequently, a switching DC-DC converter with large current driving ability and tight voltage regulation is inevitable for the voltage supply sources of ASICs or processors.
A dual-phase switching DC-DC converter has larger current driving ability than a single-phase one. Besides, the output voltage ripple can be reduced in the dual-phase architecture. However, the mismatch of two power stages in dual-phase architecture will produce current sharing between them, and system reliability decreases. Hence, the current balancing technique has to be used to improve this phenomenon. Commercial solutions for dual-phase switching DC-DC converters are almost realized by analog circuits. However, the analog control scheme is sensitive to the process variation and noise, and has low design flexibility. In this thesis, a programmable, dual-phase digital PWM DC-DC converter will be introduced. A simple current balancing approach is used to simplified loop complexity. There are only one current loop and an inherent voltage loop to calibrate difference current level between two power stages to minimize the system complexity. This controller has been realized by 0.35um CMOS process, and the functionalities of this circuit have been verified by the measurement results.
Moreover, because a switching regulator will generate electronic magnetic interference (EMI), it is necessary to add external EMI filters to alleviate this phenomenon. In this thesis, we present a frequency-modulation mechanism based on a dual-phase digital PWM to alleviate the problem of EMI. This frequency-modulation controller has been fabricated by 0.35um CMOS process, and the function of EMI reduction has been verified by the experimental results.
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