This paper describes the design of a low-power photo-voltaic power converter which will be used in a directional hearing aid. It is argued, that the use of a switched-capacitor converter is needed when integration on a chip is demanded. This converter combined with a parallel power converter has an efficiency that lies between 70% and 85%. This efficiency depends on the charging voltage of the implemented rechargeable thin-film lithium-ion battery. This battery will be glued at the back side of the power-converter chip. The converter is controlled by a maximum-power-point-tracker to perform maximum charging of the battery under the varying conditions of the solar cell. The controller is adapted to operate with a switched-capacitor converter. This paper also shows a structured derivation of the necessary solar cell area. The complete power converter has been designed in a custom CMOS process and the major part of the circuit operates in the sub-threshold area.
|Title of host publication||Smart structures and materials 1998: smart electronics and MEMS, San Diego, 1998|
|Editors||V.K. Varandan, R.A. Singer, M.J. Vellekoop|
|Place of Publication||Bellingham|
|Publication status||Published - 1998|
|Name||Proceedings of SPIE|