An LTCC Based Filter and Front End Module using Heterogeneous Dielectrics

This paper presents a multi-layered bandpass filter (BPF) and a power amplifier module (PAM) integrated with a SAW duplexer based on heterogeneous ceramic substrates. The heterogeneous substrates are composed of two different ceramic layers with εr = 7.4 and 17.5 in order to take advantage of their own properties. In the PAM substrate, a DC blocking capacitor and a shunt capacitor for an output matching network of a power amplifier are embedded with a material of εr = 17.5 to reduce occupied areas of the capacitors. On the other hand, a quarter-wave-length stripline and RF chokes are realized with a material of εr = 7.4 to reduce signal delay time. In the multi-layered BPF, a coupled stripline and a high shunt capacitor are embedded with materials of εr = 7.4 and 17.5, respectively, resulting in improved spurious characteristics.