The Balun Design by Embedding High Permittivity Material in The Substrate of CSP Package with Large Size

In order to cope with the worldwide shortage of the MLCC (multilayer ceramic capacitor), this paper proposes a methodology of integrated lattice balun using a high permittivity substrate material. It is well known that discrete radio frequency (RF) front-end circuits are composed of MLCCs and chip inductors in many electronic products. Inserting a high permittivity material to replace decoupling capacitors is an effective method. Another way to lessen the quantity of MLCCs is embedding an integrated RF front-end circuit instead of MLCCs, such as a balun, filter or duplexer. In this study, an integrated lattice balun was designed for DCS (digital cellular system) 1800 MHz. The simulation results show that the designed balun achieves a return loss $< -23$ dB, an insertion loss $\gt -0.25$ dB, a phase deviation form $180 \circ$ to $182 \circ$ and a magnitude deviation of less than 1.1 dB in the frequency range of DSC.