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http://dx.doi.org/10.7471/ikeee.2018.22.4.1006

Three Level Buck Converter Utilizing Multi-bit Flying Capacitor Voltage Control  

So, Jin-Woo (Dept. of Electronics Engineering, INHA University)
Yoon, Kwang-Sub (Inha University)
Publication Information
Journal of IKEEE / v.22, no.4, 2018 , pp. 1006-1011 More about this Journal
Abstract
This paper proposes a three level buck converter utilizing multi-bit flying capacitor voltage control. The conventional three-level buck converter can not control the flying capacitor voltage, so that the operation is unstable or the circuit for controlling the flying capacitor voltage can not be applied to the PWM mode. Also when the load current is increased, an error occurs in the inductor voltage. The proposed structure can control the flying capacitor voltage in PWM mode by using differential difference amplifier and common mode feedback circuit. In addition, this paper proposes a 3bit flying capacitor voltage control circuit to optimize the operation of the three level buck converter depending on the load current, and a triangular wave generation circuit using the schmitt trigger circuit. The proposed 3-level buck converter is designed in $0.18{\mu}m$ CMOS process and has an input voltage range of 2.7V~3.6V and an output voltage range of 0.7V~2.4V. The operating frequency is 2MHz, the load current range is 30mA to 500mA, and the output voltage ripple is measured up to 32.5mV. The measurement results show a maximum power conversion efficiency of 85% at a load current of 130 mA.
Keywords
CMOS; PMIC; 3-level; Buck; Flying capacitor;
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