High-Bandwidth Low-Insertion Loss Solenoid Transformers Using FeCoB Multilayers

High-bandwidth low-insertion loss solenoid transformers using a multilayered FeCoB magnetic core have been designed, modeled, fabricated, and characterized for high-frequency power conversion. Various transformer designs are compared in terms of inductance, resistance, quality factor, mutual coupling, and insertion loss. A mutual coupling coefficient of 0.9 up to 50 MHz is achieved for intertwined solenoid transformers with a patterned magnetic core.