| Summary: | 碩士 === 國立臺灣大學 === 電機工程學研究所 === 107 === A constant on-time buck converter with analog time-optimized on-time control (OTC) is proposed in this thesis to achieve fast load-current step-up transient response for high slew-rate loads such as Central Processing Unit (CPU) and Graphics Processing Unit (GPU). The proposed control firstly implements a constant on-time converter embedded with time-optimized control and solves the prior art issues such as poor light-load efficiency, high quiescent current, and the dependence on the power stage parameters of time-optimized control implying that the mismatched doesn’t affect the proposed OTC . The body diode control (BDC), which minimizes overshoot with simple logic and capacitor-current sensor, is proposed for load current step-down. The proposed control was implemented into an integrated circuit (IC) using 0.18um CMOS process with a chip area of 1.423mm2, where OTC only occupies 0.054mm2. The simulation results show 51.3% and 55.5% reductions of voltage deviation after enabling proposed control functions at load step-up and step-down, respectively. Measurement results show that the undershoot of output voltage improves 52.4% after enabling OTC for a 0.84A load step-up.
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