The three-level buck converter effectively reduces switching loss and is suitable for applications with higher switching frequencies and input voltages. However, three-level buck converter with conventional constant on-time control cannot scale their switching frequency with load under discontinuous conduction mode when the conversion ratio(M) is larger than 0.5. This digest introduced a novel on-time extension method to scale its switching frequency for full duty cycle range, leading to remarkable efficiency under light load condition. The chip prototype is designed using a TSMC 0.18um CMOS process. The simulation results show a 2MHz switching frequency with and a loading range from 20mA to 1A with > 90% efficiency.
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