Microtransformer with closed Fe-Co magnetic core for high frequency power applications

Abstract

This paper presents a development of a microtransformer device fabricated using MEMS technology. The device is designed for higher switching frequencies beyond to 50 MHz power applications. The microtransformer features a closed magnetic core and six identity coils (three coils on primary and three coils on secondary side). Depending on connecting technique, this design allows a wide flexibility to set different values of inductance and of transformer winding ratio. As a magnetic core material Fe-Co alloy is applied, this device shows a significant improvement compared to the first fabricated prototypes with Ni-Fe magnetic core.

A Survey on Microtransformers

“…This area has been mentioned in almost 40% of the papers analyzed in this work [15], [22], [24], [31], [39], [40], [42]- [47], [50], [52], [54], [58], [59], [62], [66], [67], [70]- [73], [79]- [81], [84]- [91], [93]- [99], [101], [105], [116], [120]- [122], [131]- [134]. Some of the examples of specific applications in this area are DC-DC converters, energy harvesting, and power systems on chip.…”

“…Since 2010 the wire bonding technique has been added to the list, although one of the first devices built with this technology appeared in an application bulletin of the Burr-Brown Corporation in 1994 [114]. One of the most versatile processes for building microtransformers with any structure and geometry, is microfabrication [2], [5], [6], [17], [22], [25], [28], [40], [49]- [51], [54], [58], [62], [63], [70], [71], [80], [81], [84], [89], [90], [92], [105], [107]- [109], [122], [128]- [130]. Of course, any of the other fabrication approaches may involve microfabrication in some of the processing steps.…”

On-chip high performance magnetics for point-of-load high-frequency DC-DC converters

“…First fabricated microtransformer device was shown before [8]. This design is improved in terms of increasing current capability and efficiency.…”

Effect of Annealing Temperature on the Coercivity and the Electrical Resistivity of the Electroplated Ni-Fe-W Alloy Film

“…We investigate the influence of annealing temperature on the H C and the resistivity of the plated alloy. The Ni-Fe-W alloy films have attracted attention due to its soft magnetic properties and are suitable for a micro-transformer magnetic core [16][17] and a magnetic recording head [18].…”