1-chip balanced FBAR filter for wireless handsets

There is great demand for ultra-miniature and balanced RF filters as an essential component in communication systems. To make these needs, we proposed 1-chip balanced FBAR RF filter in this work. A novel FBAR configuration is developed to reduce the area of FBAR block and to enhance performance. And a novel balanced filter topology which can work without trimming inductors is proposed to realize 1-chip balanced RF filter. We also develop the wafer level package using silicon wafers to prevent the increase of size and cost of the filters. The characteristic of fabricated filter is measured 1.75dB as a highest insertion loss in the pass-band (1930-1990MHz) and majority is measured as excellent performance within 1.7dB. Attenuation characteristic is measured very excellent performance as over 33dB in the range between 1850MHz to 1910MHz. In this work, the balanced RF filters are achieved as small as 1.2 mm × 1.2 mm.