First BAW Filters to Enable WiMAX and WLAN Co-Existence

Skyworks Solutions has introduced what it says is the industry's first bulk acoustic wave (BAW) filters for customer premise equipment (CPE) to allow co-existence between Wi-Fi and WiMAX networks. As both networks operate at very closely spaced frequency bands, these unique BAW filters reject the interfering frequencies while allowing the desired signals to pass for the selected network.

"WiFi and WiMAX are converging markets and OEMs have a critical need for both signals to co-exist on the same device," said Stan Swearingen, Skyworks' vice president and general manager. "Skyworks is uniquely meeting this design challenge and has introduced filtering technology to address these requirements and, in turn, support a variety of applications including access points, PCMCIA cards, USB dongles, notebook and ultra-mobile personal computers, as well as femto and pico base stations."

Filters are the first line of defense against interference at the front-end of all radios, as they block unwanted frequencies, while the desired frequency band is transmitted with very low loss. As an increasing number of communication systems use adjacent RF frequency bands, very high selectivity filters have become more critical in ensuring that those systems with close frequency bands do not interfere with each other.

A great challenge for RF filters is to provide low loss in the desired transmission band, and yet give high rejection at nearby frequencies, such as those just outside the passband. BAW filter technology is ideally suited for achieving such high selectivity since it works by transducing electrical signals into very low loss (high Q) resonant acoustic vibrations in piezoelectric structures.

BAW filters are fabricated using semiconductor wafer fabrication techniques similar to those already used by Skyworks to manufacture heterojunction bipolar transistor (HBT) PAs and pseudomorphic high electron mobility transistor (pHEMT) switches.

Posted to the site on 4th June 2008