Development of low-profile DC/DC converter using switched-capacitor circuits and coreless PCB gate drive

This paper presents the design and analysis of a low profile multi-stage current-controlled switched-capacitor (SC) step down DC/DC converter. The converter not only exhibits all the advantages of classical SC converters, but also features good regulation capability and continuous input current waveform, resulting in low conducted electromagnetic interference with other circuits. The concept of energy transfer is achieved by paralleling the input and output of two step-down converter cells and operating them in anti-phase. The voltage conversion ratio is determined by controlling the capacitor charging trajectories. As the circuit does not need to use any inductive elements, the possibilities of integrated circuit fabrication and high power density are promising. By applying the state-space averaging technique, a third-order state-space model for n-stage converter is derived. Static and small-signal dynamic behavior of the converter are investigated. Experimental measurements of a 70 W, 48 V/12 V prototype are verified with analytical predictions.