Capacitance Value Free Switched Capacitor DC-DC Voltage Converter Realizing Arbitrary Rational Conversion Ratio

Kouhei YAMADA  Nobuo FUJII  Shigetaka TAKAGI  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E87-A   No.2   pp.344-349
Publication Date: 2004/02/01
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit Techniques and Related Topics)
switched capacitor circuit,  voltage converter,  DC-DC converter,  voltage reference,  

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A switched capacitor DC-DC voltage converter that has an arbitrary conversion ratio of rational number is presented. A given voltage conversion ratio is systematically expanded to construct a switched capacitor circuit that operates with a two-phase switching clock. The conversion ratio is completely free from capacitance values and ratios under the assumption that there is no charge transfer between the two switching phases. This means that the converter cannot supply any power to the load. This restricts the application of the converters to a very limited area such as a voltage reference generator that only provides a reference voltage and no power to a circuit. The conditions for the convergence of the output voltage and the stray capacitor effects are discussed. The output voltage error and required switching frequency are also discussed when the converter is used as a DC voltage supply source that provides power to a load.