Photovoltaic-Generated Millivolt Reference Using Multiple Integrated Photovoltaic Cells

This study presents a novel voltage reference topology designed based on a self-generated millivolt reference obtained from multiple on-chip integrated photovoltaic cells. The difference in the open-circuit voltage (
${V}_{\textit {OC}}$
) between two photovoltaic cells (
$\Delta {V}_{\textit {OC}}$
) is used as the voltage reference. A heavily-doped region is formed at the silicon/contact interface, which functions as the electrical passivation that changes the order of the surface recombination velocity from
$10^{{6}}$
-
$10^{{7}}$
cm/s to
$10^{{2}}$
cm/s. Therefore, we employ one electrically passivated cell and one un-passivated cell in the proposed voltage reference topology. The illuminance-independent
$\Delta {V}_{\textit {OC}}$
, which is temperature dependent, is generated by using the two cells. Therefore, including an additional
${V}_{\textit {OC}}$
with the coefficient (
$\alpha {V}_{\textit {OC}}$
) successfully eliminates the temperature-dependency and satisfies the voltage-reference demands. We performed a numerical simulation analysis, which demonstrates that an area of <0.001 mm2 is available in the two cells topology, and a total area of 0.0014 mm2 is required to eliminate the temperature variations in the three cells topology.