A dynamically reconfigurable NRTI switched-capacitor-based hybrid DC-DC converter suitable for embedded applications

In this paper, a dynamically reconfigurable, Non-overlap Rotational Time Interleaved (NRTI) switched capacitor (S-C) DC-DC converter is presented. Its S-C module is reconfigurable to generate three different fractions (viz., 1/3, 1/2 and 2/3) of its input supply (Vdd). This maintains good power efficiency while its output voltage gets adjusted over a large range. In addition, a load-current-sensing circuit is integrated within it to dynamically reconfigure the S-C module based on the required driving capability. This feature enables to extend load current range to higher limit and at the same time improves the power efficiency in low load current regime. The S-C module is integrated with a current control loop for load and line regulation.The proposed architecture is simulated in a 0.18 μm CMOS process using dual oxide transistors to demonstrate the efficacy of the proposed topology. The input supply voltage is 3.3 V and the regulated output range is 0.8-1.6 V. Total flying capacitance is 330 pF and the load capacitor value is 50 pF. For an output of 1.35 V, its power efficiency is maintained above 50% over a load current range of 4 -17.6 mA with a peak of 66% at 9 mA. Throughout this current range the output voltage ripple remains within 12 mV.