| In modern life,the portable electronic devices,such as smart phones,tablets,are increas-ingly popuplar and fully fuctional.The performance of the application processors which plays an important role in the devices is also increasing.The power management integrated circuits,which powers the processor,is required to be improving and matchable.In this thesis,the Buck converters with high frequency,fast response and large current is studied.By the analysis and comparison on different control strategies,the hysteretic con-trol strategy with fast transient response is adopted as the system architecture and optimized to overcome the shortcomings of the traditional hysteretic control structure,and a fixed switching frequency and an accurate output voltage are achieved.According to the design specifications,the inductor and output capacitance is determined.To improve the load current ability and the load transient response ability,the Buck converter is expanded from single-phase to dual-phase.Besides,a current balance scheme is proposed to eliminate the current imbalance caused by multiple phase mismatches.And low-power and high-precision current sensing at high fre-quencies is realized by chopper technique,and the sensing accuracy is as high as 99%.In order to improve the efficiency of a wide load range,the Buck converter can switch the number of phases depending on the load current.The design of other modules are also implemented,such as high-speed comparators,bandgap,clock generator,etc.The chip uses 0.18?m BCD process.The input voltage range of the designed Buck con-verter is 3.3 V?4.0V,the output voltage is 1.8V,the maximum load current is 3A.The simulation results show that the Buck converter can work normally with the switching frequency 50MHz.The output voltage ripple is less than 1.8mV,and the peak efficiency reaches 81.3%.When the load current changes at a rate of 1A/ns,the output voltage does not change more than 50mV,and the loop response time does not exceed 400ns. |
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