Packaging-compatible microtransformers on a silicon substrate

Abstract

Surface micromachining techniques are utilized to realize iiiicrotransforiners for being integrated with a multi-chip package, allowing compact integration with chips, sensors, and other components. Two different microtransformers with two-layer vertically stacked spiral-type copper conductor lines and permalloy magnetic cores have been designed and fabricated. Low temperature processes are only chosen for fabricating these microtransformers. The fabricated microtransformers have been tested and compared for finding out better geometries for microtransformers. Electroplated thick permalloy cores and copper coils are utilized for obtaining better performance characteristics in the intermediate frequency range.The fabricated microtransformer has a turn ratio of 1, coupling coefficient of 0.85, dc resistance of 3.3 ohms, and gain characteristics of -5dB, respectively. These devices have high current capability (up to 2A steady DC current) and are suitable for low power converter applications.

Design, fabrication and testing of sandwich coupled inductors

“…These parasitic effects become dominant at high operating frequency, hence lower the inductor performance. Furthermore, the limitation on the required chip area, the spread out of the magnetic flux path outside the coil as well as high flux leakage have further reduced the magnetic coupling capability of the coupled inductor (Chong and Xie 2005;Park and Bu 2003;Yue and Wong 2000).…”

High efficiency Si integrated micro-transformers using stacked copper windings for power conversion applications

“…Solenoid type microtransformers are fabricated using multilevel metal schemes to wrap the coils around a magnetic core [1]- [4]. Single deposition of the magnetic core automatically provides a completely closed magnetic circuit, and hence minimizes leakage flux.…”

“…Much of the previous works have focused on the microfabrication and test of micro-transformers for isolation [1][2][3][4][5][6][7]. Solenoid type microtransformers are fabricated using multilevel metal schemes to wrap the coils around a magnetic core [1]- [4].…”

A New Fractal-Based Design of Stacked Integrated Transformers

“…Due to a growing need for wireless communication devices, radio frequency and wireless market is continuing its development. The integrated transformer is an essential component in many RF and microwave integrated circuits [1][2][3][4][5][6][7][8]. Although significant efforts have been made in order to improve the characteristics of integrated transformers [9][10][11][12], it is still a great problem to bring in piece the opposite demands for low cost, low supply voltage, and low power dissipation, but small occupied area and high frequency of operation in RF implementation of these transformers.…”