Ring type Switched-Capacitor DC-AC Converter

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The requirement of the low power dissipation of switched-capacitor (abbr. SC) power supplies, which use many MOSFET switches for the performance of the circuit exchange, is recommended to adopt n-channel MOSFETs and a high gate-driving voltage. This second requirement is a deep problem in boot-up power supplies, because the last stage of boot-up circuits can not utilize any excess voltage than the power source except adopting an additional boot-up circuit. For this purpose, a novel boot-up circuit of simple circuit configuration is proposed. Furthermore, a power saving mode is adopted for this purpose.The proposed circuit provides sufficient power voltage to gate drivers. Therefore the DC-DC converter using the proposed gate driver gives a high conversion efficiency of 92% under the power source voltage of 3.8V. The proposed driving circuit is shown to make the best use of a ring-type SC power supply. The additional circuit is constructed only by several switches and one capacitor.The power-saving mode can reduce the power consumption effectively. This performs to make all clocks (driving signals) inactive according to the standby signal active, therefore the all switches turn off and the input/output terminals are separate from the power source and the load. These experimental results and simulation results are presented at the international conference (ITC-CSCC 2002, The 2002 International Technical Conference on Circuits/Systems, Computers and Communications).For backlighting of mobile equipment displays such as PHS, electroluminescent (abbr. EL) is extensively requested. For this usage, very small SC power supplies are experimentally produced on a chip. A size of the bare-chip power supplies is 6.8mm square×3mm thickness within 4 external boot-up capacitors. The output power is limited at the present time by the manufacturing method of the channel structure, but the low noise and extremely small size power supplies gave a bright vista.