Fully embedded CDMA cellular-band lumped LC-quadrature hybrid coupler into organic package substrate

In this paper, fully embedded lumped LC-quadrature hybrid coupler are designed, fabricated, and characterized into multi-layered organic packaging substrate. This embedded device is comprised of high Q MIM capacitors and circular spiral stacked inductors. For realizing fully embedded high Q capacitor, barium titanate (BaTiO3) composite high Dk film was utilized. The measured return loss and isolation are better than 25dB. Measured insertion loss is about 0.38 ~ 0.42dB at the frequencies ranged from 824MHz to 894MHz (CDMA cellular-band). The coupler exhibits a coupling loss of 23.3 ~ 24dB. The phase difference between through and coupling ports is 1.2 ~ 2.4 degree. It has a size of 2.8mm × 2.95mm × 0.66mm (height), which is the smallest one in the couplers developed onto the package substrate. The measured performance characteristics are well matched with the 3D EM simulated ones.