| Summary: | 碩士 === 國立交通大學 === 電機工程學系 === 105 === This thesis presents a novel high-efficiency, fast-transient, and low-cost current-voltage dual-mode (CVDM) dc-dc buck converter using adaptive clock controller (ACC). The proposed CVDM control can switch the control method between current mode and voltage mode to improve the performance according to different situations. By using the ACC technique, the circuit can dynamically and smoothly adjust the switching frequency during the transient response to improve the undershoot, overshoot voltage, and recovery time. Moreover, the proposed on-chip soft-start circuit can eliminate the excess large current during the startup of the regulator. In this work, only an output inductor, capacitor, and feedback resistors are outside the system on chip (SoC), so the chip area and the cost can be reduced effectively. The circuit was implemented by TSMC 0.35-μm CMOS process. The input voltage is 2.7~4.2V and the output voltage is 0.9~2.7V accordingly, which is suitable for portable devices. The transient recovery time and undershoot voltage are less than 5μs and 94mV, respectively, for the load current change from 50mA to 500mA. As compared with the traditional structure without any fast transient technique, the performance of transient recovery time and undershoot voltage can be reduced by 83% and 36%, respectively. The maximum conversion efficiency is 95.784% at 100mA load current. Above 90% conversion efficiency can be achieved for load current from 30mA to 600mA. With the proposed techniques, the performance of the dc-dc converter is improved significantly.
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