BAW filter

BAW filters ( engl. Bulk acoustic wave ) are electronic filters with band-pass characteristic. They are used in high-frequency technology, for example in cellular communications and WLAN . The way it works is comparable to that of a surface acoustic wave filter ( SAW filter ), but with the difference that the BAW filter propagates the acoustic waves in the substrate (bulk) .

Due to their better electrical and physical properties, BAW filters are increasingly replacing the previously widespread SAW filters . In contrast to SAW filters, BAW filters have smaller sizes, lower insertion loss (<0.5  dB ), a better temperature coefficient (around 20 ppm / Kelvin) and are less sensitive to electrostatic discharges (ESD). Another advantage is the lower production costs, since BAW filters are based on CMOS technology and therefore no special materials are required for special substrates.

BAW filters achieve a quality factor of over 1000 and are available for frequencies from around 1  GHz to 20 GHz.