一般電子產品中，多半會加入電源控管電路，如直流-直流轉換器來將前端的供應電壓源轉換為穩定的輸出電壓以供內部電路使用。因此對於高轉換效率、高精準度且體積小之直流-直流轉換器的需求愈來愈高。交換式電源轉換器具有大負載電流範圍以及高轉換效率的優點，但是架構中採用電感以及電容當作能量傳遞的元件，而且在主迴路中的功率電晶體是當作開關來使用，因此輸出電壓具有漣波。而線性穩壓器架構中的功率電晶體並非當作開關來使用，所以無輸出電壓漣波，但缺點是當輸入與輸出電壓的差距加大時，轉換效率會降低。有鑒於此，本論文提出一個結合交換式電源轉換器以及線性穩壓器的降壓型直流-直流轉換器架構，結合兩種架構的優點，並提供兩組穩定的輸出電壓。
本電路透過國家晶片系統設計中心提供的製程服務，使用台灣積體電路公司0.35μm 2P4M 5V混合訊號製程，以40 S/B封裝，尺寸為1.67×1.70mm2。量測結果如下：線性穩壓器部分，負載調節率為0.24mV/mA，無載時的電源調節率為9mV/V，最大效率為91.626%；降壓型切換式電源轉換器部分，負載調節率為0.46mV/mA，輕載時的電源調節率為75mV/V，最大效率為87.01%。

Power management circuit, such as DC-DC converter, is widely used in electronics to convert power supply to a required stable output voltage for electric circuits. Therefore, there is an increasing demand for the DC-DC converters with high efficiency, high accuracy, and low cost. Switching regulators have the advantages of wide load current range and high efficiency, but their inevitable output ripples is a problem for noise-sensitive analog circuit. On the other hand, linear regulators ideally have no output voltage ripple, but their efficiency drop significantly when the difference between the input and output voltages increases. Therefore, in this work, a low-dropout linear regulator is connected in series with the Buck converter to provide a 3.3V ripple-free output voltage for analog circuit, while the output of the Buck converter, which is 3.6V, is directly provided for digital circuit.
The die area of the proposed chip is 1.67×1.70mm2. The chip was implemented by Taiwan Semiconductor Manufacturing Company (TSMC) 0.35μm 2P4M 5V mixed-signal polycide process, patronized by National Chip Implementation Center(CIC). For the LDO, the measured load regulation is 0.24 mV/mA, the measured line regulation at no load is 9 mV/V, and the max efficiency is 91.626%. For the Buck converter, the measured load regulation is 0.46 mV/mA, the measured line regulation at light load is 75 mV/V, and the max efficiency is 87.01%

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