Bandpass Filters Design in the Organic Substrate without Using Large-Value Capacitors

Very small-size bandpass filters embedded in the organic substrate for wireless front-end applications are presented. Due to the lack of fabrication process for large-value capacitors in the organic substrate, a novel filter prototype using an inductive coupling of series resonators is proposed to achieve high performance within a stringent size constraint. In implementation, the organic bandpass filters are composed of the spiral inductors and parallel-plate capacitors that are embedded in a 4-layer BT laminate, one of today´s most popular package substrate. The final realized performance and size are competitive to the LTCC filters but with a much lower cost