A Pfm Step-up Dc / Dc Converter Design

Along with the great development of portable equipments market and the emergence of new functions, the power supply accommodation and power supply management industry are encountering an enormous technology challenge. At present, many advanced integrated circuit design manufactures give their eyes on the power supply management, dedicating to the design and search on how to increase power supply converting efficiency and improve the product performance, and even more and more semiconductor manufactures join in such field. Step-up DC/DC converter is one of the most important branches in the power supply management, and therefore is also paid wide attention.A PFM controlled step-up DC/DC converter is analyzed in this thesis. The chip takes the 0.5μm standard CMOS process. The input voltage range is from 0.9V to 2.0V, and the output voltage is 3V. The control scheme is Pulse Frequency Modulation (PFM). Shut-down mode is one other feature, and then the standby current is no more than 0.5μA. The temperature range is -30℃~ 80℃.The topology of the step-up DC/DC converters and its basic principle is first analyzed in this thesis. Then based on the conventional PFM control scheme, a Discrete Pulse Frequency Modulation is presented and the state space average model related to the CCM (continue current mode) and DCM is established. Further, the characteristics such as the response speed, the efficiency and the relationship between load and the modulation factor are counted and analyzed. During the stage of circuit design, the whole chip and the sub-block circuits are well-designed, respectively. The author pays more attention to the analysis and design on the following sub-circuits: Oscillator, Comparator, Hysteresis Comparator, Chip Enable, etc.On completing the principle analysis and circuit design, the sub-circuits and whole chip circuit are verified with the EDA tools HSPICE. The simulation results are all in accordance with the theory analysis, some even better than the theoretical specification. The basic principle of Discrete Pulse Frequency Modulation on step-up DC/DC converter is testified, and this effort accumulates more experience to design...