A ring type step-up switched-capacitor dc-dc converter that has low inrushcurrent at start-up and low current ripple in the steady state

A novel type de-de converter is presented that consists of rt ring-shaped c apacitors connected by switches. The proposed method is totally different f rom conventional switched capacitor (SC) transformers. Although converters using SC do not contain both inductors and resistors, and the magnetic fiel d generated is extremely slight, they have the following disadvantages: (1) The inrush current is large, (2) the input and output current ripples are large, and (3) the driving circuit becomes complex because a lot of floatin g switches are needed. Because only one capacitor is charged at one time in the proposed converter and all floating switches form a totem-pole connect ion with grounded switches, the inrush current and the input current ripple are small, and the driving circuit becomes simple. The proposed converter has the following advantages compared with the conventional SC converters: (1)The inrush current is small, (2) the input and output current ripples ar e small, (3) the number of switches is less than that of the conventional S C converters, (4) it is easy to drive the switches, and (5) the proposed ci rcuit is suitable for fabricating in an IC form together with other signal circuits (such as system-on-chip) because the proposed circuit has no magne tic parts (such as a coil or a transformer) and the magnetic field generate d is extremely small. (C) 1999 Scripts Technica.