A compact dual-passband filter based on bulk acoustic wave technology

A compact RF dual-passband filter based on bulk acoustic wave (BAW) technology is designed and fabricated for wireless applications. Such a compact filter has promising uses in handheld devices where dual-standard systems would be used. The dual-passband filter is achieved by two band-pass BAW filters with shared input and output ports. A simple matching network is used to provide high performance dual-passband response with little mutual degeneration. The measured insertion loss is around 2.0 dB typically in both the lower and the upper passbands, and the filter rejections out of the passbands are more than 30 dB.