本論文採用脈衝寬度調變(PWM)及突衝模式(Burst mode)來實現高效率同步式降壓型穩壓器。此穩壓器重載時操作於脈衝寬度調變模式，而輕載時操作於突衝模式。輕載時，穩壓器的主要損耗為切換損失，故藉由降低切換頻率與加入零電流偵測電路，以提升轉換效率。
規格如下：輸入電壓為5 V，輸出電壓為3.3 V，PWM模式下切換頻率為1 MHz，而突衝模式下為700 kHz。200mA以下操作於突衝模式電路，而200 mA以上操作於PWM電路。藉由選擇此兩種不同的工作模式，轉換器在大範圍的負載下，均可達到最佳的轉換效率。在突衝模式下，當負載電流為70 mA最高效率可達88.17%，在PWM模式下，負載電流為400 mA最高效率為94.28%。

This thesis implements a high-efficiency synchronous buck converter with pulse width modulation (PWM) or Burst mode. The buck converter operates with PWM at heavy load and with Burst mode at light load. The dominant power loss of dc-dc converters at light load is switching loss. Therefore, the converter efficiency can be improved by reducing the switching frequency and adding zero current detector circuit.
The specifications of the buck converter are the input voltage of 5 V, output voltage of 3.3 V, and the converter switching frequency of 1 MHz at the PWM mode or 700 kHz at the Burst mode. The buck converter operates at the PWM Mode when the load current is higher than 200 mA, or the converter operates at the Burst mode. The presented converter with these two operation modes achieves optimal efficiency at a wide range of the load current. The maximum efficiency with the Burst mode is 88.4% at load current of 70 mA. At the PWM mode, the maximum efficiency is 94.8% at loading current of 400 mA.

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