Integration of Series-Connected On-Chip Solar Battery in a Triple-Well CMOS LSI

A method of constructing a series-connected on-chip solar battery for integration into system LSIs using a triple-well CMOS process is presented. The triple-well CMOS process has various advantages, i.e., CMOS circuits are independent of the substrate voltages integrating series-connected on-chip solar batteries and have no leakage problems. The advantages of this method have been proved by ring oscillator operations with a solar battery voltage of 1.3 V, which is higher than those of single and conventional series-connected solar batteries. The current versus area optimization for series-connected solar batteries is considered.