Integrated Transformers With Sputtered Laminated Magnetic Core

Integrated interleaved solenoid transformers with a single layer of laminated magnetic core have been designed and fabricated. A coupling coefficient of > 0.97 was achieved for a device with a primary and secondary inductance of 565 nH, which represents an enhancement of more than 60 times that of air core inductors of identical geometry. By using the laminated magnetic core structure, the quality factor of the primary or secondary inductance was increased to a peak value of 6.3 with 3 μm thick electroplated copper coils. Measured characteristics of the integrated transformers agree very well with simulation results for values of self-resonant frequency, inductance, quality factor, and coupling coefficient.