A miniaturized monolithic dual band filter using ceramic lamination technique for dual mode portable telephones

A miniaturized monolithic dual band filter is developed for dual mode portable telephones. By using a ceramic lamination technique, a 1 mm-thick 900 MHz filter and a 1.9 GHz filter are fabricated and stacked to be co-fired. The performance degradation due to the thickness and the dual band matching network are discussed. An experimental filter is constructed and shows very good performance.