Dual-source hysteretic switched-inductor 0.18 µm complementary metal–oxide–semiconductor charger-supply system

Although miniaturised fuel cells store more energy than lithium-ion batteries and super capacitors, they source less power, which means they cannot power as many functions. Their power-dense counterparts, however, cannot sustain life for long, which is why mixing technologies is appealing. Still, microsystems are tiny and react quickly, so their supply circuits must also be small and fast. For this reason, the dual-source hysteretic single-inductor 0.18 μm complementary metal-oxide-semiconductor charger-supply system presented and discussed here draws constant power from an energy-dense source and supplementary power from a rechargeable power-dense battery. The prototyped system supplies and responds to 1-4 mA load dumps within one or two clock cycles with 73% peak efficiency and recharges the battery with excess power from the energy-dense source. When managed to draw supplementary power from a battery this way and loaded with a microsystem that idles at 10 μW and peaks to 4 mW, as in the case of typical wireless sensors, the combined weight of the sources required is 68% less than those of the state-of-the-art.