Microwave and Magnetostatic Characterization of Ferrite LTCC for Tunable and Reconfigurable SiP Applications

The material property extraction techniques for an emerging commercial ferrite LTCC (low temperature co-fired ceramic) tape are presented. These properties are evaluated in the context of tunable and reconfigurable microwave components for wireless communications. Relevant parameters for microwave design, including relative permittivity epsiv_r, relative permeability mu_r and loss tangent tandelta, are presented. Measurements performed at 9.86 GHz and 27.2 GHz yield an epsiv_r of 13.6 and tandelta values of 0.004 and 0.001 respectively. For the first time, a completely embedded LTCC toroid transformer is utilized to extract the magnetostatic properties with greater accuracy than a solenoid transformer. These measurements reveal a saturation flux density of nearly 400 mT, a remanence of 250 mT, and a coercivity of 430 A/m. The peak relative linear permeability of the ferrite is 370. The low loss tangent and the high degree of variability of the ferrite properties with bias indicate its suitability for tunable and reconfigurable microwave SiP (system in package) applications.