Embedded hybrid DC-DC converter with improved power efficiency

This paper deals with the efficiency improvement of an embedded hybrid DC-DC converter which is suitable for high dropout embedded regulation. In the proposed topology, power efficiency is improved by eliminating shoot-through current of switched-Capacitor module using Non-overlapped Rotational Time Interleaving (NRTI) switching scheme. In addition to the improvement in power efficiency, this scheme also reduces output voltage ripple. As the output of the switched capacitor network is a function of load current and switching frequency, the switched capacitor network is cascaded with a linear regulator to get line and load regulation. The proposed hybrid converter circuit is designed in 0.18 mu process for 3.3 V to 1.25 V conversion. With total flying capacitance of 330 pF, for 15.5 mA of load current and 50 pF load capacitor, peak-peak output voltage ripple is only 6 mV and the achieved power efficiency is 70%.