為了改善在不同輸出負載下的切換頻率，本論文提出使用漣波調變定截止時間控制的降壓型轉換器 並加上隨負載變頻機制和波峰電壓切換機制，提升轉換效能。一般來說，輕載時轉換效能由切換損耗主導功率 開關切換若使用硬切換控制會導致損耗較大使效率降低。本文所提出的波峰電壓切換機制能讓切換 損耗降低。重載時因為整體電路操作於連續電流模式(CCM)且加上本文提出的隨負載變頻機制(VFC)使電路能維持在較高的轉換效能。
本晶片以TSMC T25HVG2製程實現，晶片面積含PADs為3.01×1.34 mm2。功率級電壓輸入與控制級電壓輸入皆為5V、輸出電壓1.8V，切換頻率為500kHz，外接電感與電容分別為6.9μH與10μF，負載範圍為 50mA至1A。當負載為100mA時，使用PWM控制來輔助切換頻率定頻；當負載為150mA時，波峰電壓切換機制便會啟動使輕載時的切換損耗下降；當負載為 500mA時，隨負載變頻機制便會啟動，試著讓重載時的切換頻率下降。

In order to improve the switching frequency under different output loads, this thesis proposes a buck converter using Fixed Off-time Control, and adding a variable frequency control with load and a peak voltage switching mechanism to improve the conversion efficiency. In general, the conversion efficiency is dominated by the switching loss at light load. If the power mosfet uses hard switching control, the switching loss will be large and conversion efficiency will be reduced.The peak voltage switching mechanism proposed in this paper can reduce the switching loss. During heavy load, the overall circuit operates in continuous current mode (CCM) and Variable Frequency load following Control (VFC) proposed in this paper enables the circuit to maintain high conversion efficiency.
The chip had been implemented with TSMC T25HVG2 technology and the size of chip including pads was 3.01×1.34 mm2. The power stage voltage input is 5V and the control voltage input is 5V. The output voltage is 1.8V and the switching frequency is 500k Hz. The external inductance and capacitance are 6.9μH and 10μF. The output load range is 50mA to 1A. When the load is 100mA, the PWM function is turned on to assist the switching frequency to a constant value; when the load is 150mA, the peak switching mechanism is turned on to reduce the switching loss at light load; when the load come to 500mA, variable frequency control with load will be turn on, it will reduce the switching frequency at heavy load.

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