design and fabrication of a 315 μh bondwire micro transformer for ultra low voltage energy harvesting

• DOI: 10.5555/2616606.2616781
• Publication Date: 2014-01-01
• Authors: MACRELLI, ENRICO; Ningning Wang; Saibal Roy; Michael Hayes; PAGANELLI, RUDI P...; TARTAGNI, MARCO; ROMANI, ALDO
• Keywords: energy harvesting; PCB; magnetics; 0211 other engineering and technologies; 02 engineering and technology; converter; 7. Clean energy; DC-DC; ferrite; on-chip; bonding wires; bondwire; transformer; DC-DC CONVERSION; impedance measurements; ENERGY HARVESTING; POWER TRANSFORMER; bonding wire magnetics; PCB

This paper presents a design study of a new topology for miniaturized bondwire transformers fabricated and assembled with standard IC bonding wires and toroidal ferrite (Fair-Rite 5975000801) as a magnetic core. The microtransformer realized on a PCB substrate, enables the build of magnetics on-top-of-chip, thus leading to the design of high power density components. Impedance measurements in a frequency range between 100 kHz to 5 MHz, show that the secondary self-inductance is enhanced from 0.3 ?H with an epoxy core to 315 ?H with the ferrite core. Moreover, the micro-machined ferrite improves the coupling coefficient from 0.1 to 0.9 and increases the effective turns ratio from 0.5 to 35. Finally, a low-voltage IC DC-DC converter solution, with the transformer mounted on-top, is proposed for energy harvesting applications. © 2014 EDAA.