A 12V-to-1~1.8V Tri-Path Series-Capacitor Converter with Reduced Inductor Current and Full-Range Duty Cycle for Point-of-Loads Application

This paper presents a tri-path series-capacitor buck converter with reduced inductor current and full-range duty cycle. Aiming for high step-down conversion ratio, the proposed converter uses three flying capacitors to relieve the switch voltage stress, making the low-voltage power MOSFET available. Besides, during the inductor demagnetization period, the flying capacitors constitute the capacitive current paths directly to the output, reducing the average inductor current and hence decreasing the conduction loss. Moreover, thanks to the single inductor and two-state operation per cycle, not only is the capacitor voltage automatically balanced, but also the inherent full duty cycle operation is achieved. Validated in a 180-nm BCD technology, the proposed converter regulates a 1 V – 1.8 V output voltage from a 12 V input voltage, and it achieves a high peak efficiency of 95.6%, with a switching frequency around 1 MHz.