Multi-band RF SAW filter for mobile phone using surface mount plastic package

In recent years, multi-band RF SAW filters for mobile phone are strongly required. In this work, as the example of multi-band SAW filters, we report PDC triple-band SAW filter and EGSM /DCS dual-band balanced SAW filter using surface mount plastic package. These filters are encapsulated in plastic package and they are made by our new plastic molding technology. The plastic package has advantages of lightweight low material cost and low assembly cost. To integrate plural filters to one chip, we refined the conventional lift-off method. The method can realize easy fabrication of SAW chip for multi-band filter We utilized 36Y-X LiTaO₃ for substrates for the filter. The electrode structure of each filter is longitudinal-mode resonator filter With regards to PDC triple-band filter, we achieved typical insertion loss of 2.0 dB / 2.1 dB / 2.2 dB with bandwidth of 33 MHz / 15 MHz / 24 MHz for 800 MHz (called CD-band) / 800 MHz (called A-band) / 1.5 GHz, respectively, with excellent high rejection levels. And for another application of the plastic package, we developed EGSM/DCS Rx dual-band balanced SAW filter. We achieved insertion loss of 2.2 dB / 3.0 dB for EGSM and DCS filter, respectively, with good amplitude and phase balance. We could realize multi-band SAW filters using the plastic package and could confirm its usability for SAW devices.