| The development of portable electronics is soaring in recent years. Powering requirements of new and future high-performance, high-speed and high-integration density load of DSPs and microprocessors are becoming more stringent.More devices are being packaged on a single chip, causing higher load current. Moreover, such load speeds are increasing, and they switch the current with increasingly higher slew rates causing larger voltage deviation during their transients.Thus, the need for DC-DC converter with fast transient response is becoming more and more important. Meanwhile, they should maintain high-efficiency and high power density. In this thesis, the design and implementation of integrated, high efficiency, fast-transient DC-DC converter is comprehensively and thoroughly investigated.Control methods of DC-DC converter are firstly reviewed.The principle of one-cycle control is studied through theories and empirical analysis.The method realizes fast-transient line response through one-cycle integration. However, as output voltage can not be directly regulated when load transient happens, the load-transient response speed is limited to a large extent.On the other hand, the control scheme is difficult to be integrated.Then, an integrated dual-loop one-cycle control scheme is proposed. The control principle is discussed based on the system small-signal models. Through time-domain and frequency-domain simulation, the theoretical analysis is being verified. The method improves load-transient response while maintaining fast line-transient response through one-cycle integration of both input and output voltage.A fully integrated one-cycle controller system to realize energy conversion and control is proposed. The influence of external components on output ripple voltage and performance of load-transient response is thoroughly discussed. And based on the discussion, the parameters of the external components are chosen. The system utilizes PWM/PFM dual mode control to increase the efficiency under a wide range of load current. An improved PFM technique is propose, though which the minimum battery current is largely reduced and output ripple voltage is set by voltage clamping and current limitation with relative simple analog electronics. Moreover, a compact current-mode soft-start scheme is proposed and successfully applied to typical voltage mode DC-DC switching converters. Simulation results show that when starts up, the maximum overshoot by the proposed soft-start scheme is less than that with the conventional scheme by 5% under the same condition.A fully integrated one-cycle controller chip for high frequency, high efficiency DC-DC converter is designed. The key techniques of controller circuits are studied. A design of high intrinsic accuracy bandgap reference for current-mirror mismatch is proposed. The simulation results show that the error caused by current-mirror mismatch has been reduced by about 50 times in the proposed bandgap core. Moreover, optimum design of oscillator and transductor amplifier circuits are also presented. The compact soft-start circuit and PWM/PFM detector are designed to realize soft-start and mode-switching functions.Finally, based on BCD 0.6μm technology, a fully integrated one-cycle controller chip for high frequency, high efficiency DC-DC converter is realized. The simulation results successfully verify the control principle and show that the converter can implement high-efficient voltage conversion (maximum 94% efficiency). When starts up, the output volage rises stably with maximum 2.9% overshoot. The controller demonstrates equal or better transient-response performance compared to state-of-the-art analog switchers. Moreover, the controller can be fully integrated which results in lower cost. |
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