A 100-mW fully integrated DC-DC converter with double galvanic isolation

This paper presents a fully integrated DC-DC converter with on-chip double galvanic isolation. The converter exploits only two dice both fabricated in a 0.35-μm BCD technology with a thick-oxide back-end for 5-kV galvanic isolation. It uses a novel architecture to transmit power across two isolation barriers, which are performed by integrated capacitors and transformers. LC coupling inherently enables the resonant mode operation for the isolation network, thus increasing the conversion efficiency compared with merely series-connected isolation components. Measurements of the double isolated DC-DC converter, including a Schottky diode full-bridge rectifier, achieve 110-mW dc output power and a power efficiency of 17% setting 3.3 V for both power supply and output voltage.