零電壓開關降壓變換器提供最大功率密度、效率

　　與傳統的脈沖寬度調制（PWM）或硬開關結構相比，使用諧振拓撲的降壓變換器比基于傳統結構的電源提供更高的性能。雖然晚了傳統高密度、硬開關穩壓器具有演化的改進的半導體集成、低電阻MOSFET，和先進的包裝，他們的設計是不足以滿足新的電力需求，主要是由于在調節MOSFET的開關損耗，提高開關頻率或增加輸入電壓。

　　此外，傳統的降壓穩壓器表現出更高的柵極驅動損耗，由于米勒電荷消耗在柵極驅動電路。同樣，高側MOSFET的體二極管傳導有助于更高的功率損耗，由于反向恢復和長導（圖1）。因此，必須克服或大幅降低這些損失，以實現調節器性能的任何顯著提高。此外，硬開關拓撲需要一個比較大的輸出電感，這增加了調節器的尺寸和成本。

　　Figure 1： In conventional buck regulators， the hard-switching transition and body diode reverse recovery expose the high-side MOSFET Q1 to very high turn-on losses.

　　Benefits of zero-voltage switching

　　Another， better alternative is to use resonant topology like zero-voltage switching （ZVS）， which enables operation at higher frequency and higher voltages without sacrificing efficiency and size. The ZVS-based regulators are also known as soft-switching regulators. Some key benefits of ZVS buck regulator topology include low turn-on losses， negligible body diode conduction time due to ideal rectifier switching， high-frequency operation maintained at high input voltage， simple internal compensation – which allows for high bandwidth， gain， and phase margin – and fast transient response with a small amount of output capacitance. What is more， it offers 20 ns minimum on time to support very high conversion ratios and delivers excellent light-load efficiency due to a high-efficiency biasing system combined with pulse skipping.