Design of photovoltaic device and DC-DC converter on a single chip using 0.18 μm standard CMOS technology

In this paper, we propose a photovoltaic power supply for a stand-alone system that provides electrical generation and voltage boost functions on a single silicon chip. This power supply consists of solar cells, an oscillator, and a bootstrap charge pump, which are all designed in a 0.18 μm standard complementary metal-oxide semiconductor technology. Two types of solar cells are embedded in the system to improve its power efficiency. One type is used for the power supply and the other type is used to provide the voltage bias. Three different solar cells structures were designed. A pn structure and an np structure are used for the power supply cells and an npn series-connected structure is used for the oscillator circuit to operate the DC-DC converter The voltage-current characteristics of the solar cell under microscopic illumination have been measured and the performance of bootstrap charge pump circuits was confirmed. We remodeled our solar cell equivalent circuit to reflect these measurement results.