| The core of modern electronic systems is power supply whose performancedirectly affects the quality of electronic equipments. Because of its high efficiency,small volumn and high reliability, DC-DC converter has been wildly utilized as powersupply in various electronic equipments. Aiming at different applications,high-performance control methods of monolithic high-power DC-DC converters havebeen studied and designed in this dissertation. Therefore, under different applications,the performance of DC-DC converters can be highly optimized. High-power LEDdrivering and high-power power supply convertion are two important research areas ofrecent developments in the field of high-power power management integrated circuits.This work mainly does some analysis and studies in these two areas.High-power LED driver is one kind of DC-DC converters with large output current,whose conduction loss plays a dominant role. Taken system efficiency and chip areainto condieration, a reconfigured BUCK topology with NMOS power transistor, whichhas no requirement for bootstrap circuit, is presented in this thesis. Considering thecurrent change of high-power LED is quite dramatic, hysteretic current-mode control isselected as the control method, which is self-stable and can implement fast responsespeed and good stability without additional compensation circuit. Since there are largedv/dt and di/dt in high-power LED driving, Electro-Magnetic Interference (EMI) isserious. With regard to the unfixed frequency of hysteretic current-mode control, afrequency jitter method suitable for hysteretic current-mode control is proposed, whichcan decrease the EMI.Aiming at high-power power supply conversion application, a synchronous BUCKstructure with all NMOS power transistors on the basis of bootstrap technique isadopted to improve efficiency. On the strength of the DC model and AC model of thisstructure, this thesis tries to base on operational amplifiers to emulate the characteristicsof capacitors and inductors in order to implement active capacitors and active inductors,and an internal frequency-compensation is proposed, which can realize on chip PID compensation without capacitors as huge as several nFs in conventional methods. Theinternal frequency-compensation not only simplifies chip’s external circuit design, butalso enhances the circuit’s transient response speed and output precision. Besides, anadvanced two-stage current protection strategy is presented in this thesis, which not justguarantees the accurancy of cycle-by-cycle current limit, but protects the converter fromgetting damaged under all the loading conditions. In order to suppress high-frequencyEMI, piecewise gate driving is employed in power transistors.Voltage reference is an indispensible building block in DC-DC converters, and itsperformance directly influences the characteristics of the whole system. Thisdissertation designs high-precision, highly stable BiCMOS and CMOS referencecircuits respectively according to different process environments. On the one hand ahigh-performance BiCMOS reference has been proposed which is based on piecewisenonlinear temperature compensation technique. The active area of the reference is180μm×220μm with a maximum current consumption of25μA. Temperation coeiffiecnt(TC) is5ppm/℃, power supply noise attenuation (PSNA) without filtering capacitor is70dB, and line regulation is0.47mV/V. On the other hand a high-performance referencewithout resistors has been proposed, which is compatible with digital CMOS process.The active area of the reference is160μm×140μm with a maximum currentconsumption of27μA. TC is10.2ppm/℃, and PSNA is58dB.The study of this dissertation covers common application environments ofhigh-power DC-DC converters, and proposes relevant methods for improvementsaccording to different applications. Furthermore, the reference which is an importantbuilding block in DC-DC converters has been studied and designed. The proposedcircuits and theories have been verified by circuit design, simulation and test methods. |
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