FBAR Duplexers Help Shrink PCS/UMTS Handsets

May 17, 2006
These components make the most of advanced FBAR technology and Microcap chip-scale packaging techniques to pack a pair of filters into a tiny housing.

Small handsets require small components. Avago Techologies is no stranger to designing and fabricating miniature active and passive components for both cellular handsets and infrastructure equipment. Using their proprietary film-bulk-acoustic-resonator (FBAR) technology, the company has developed a pair of duplexers that are suitable for a variety of wireless applications, including US Personal Communications Service (PCS) and Universal Mobile Telecommunications System (UMTS) handsets. The FBAR technology supports components that are a fraction of the size of competing components fabricated with ceramic or surface-acoustic-wave (SAW) technologies. The model ACMD-7402 duplexer is designed for PCS applications from 1930.5 to 1989.5 MHz while the model ACMD-7601 duplexer is suited for UMTS applications in the receive band from 2110 to 2170 MHz and the transmit band from 1920 to 1980 MHz.

Avago Technologies, which began life as the components development group within Hewlett-Packard Co., became part of Agilent Technologies when that company split off from Hewlett-Packard. In 1999, Agilent chose to split off its former Semiconductor Products Group, which was eventually acquired by investors Kohlberg Kravis Roberts & Co. (KKR) and Silver Lake Partners in 2005 and renamed Avago Technologies to become the world's largest privately owned semiconductor company.

Both duplexers benefit from the firm's Microcap bonded-wafer chip-scale packaging technology (see figure).The packaging the process allows the filters to be assembled in a molded chip-on-board module that is less than 1.3 mm high with a footprint of only 3.8 3.8 mm.

The ACMD-7402 duplexer is optimized for the US PCS band where handset transmit signals range from 1850.5 to 1909.5 MHz and handset receive signals span 1930.5 to 1989.5 MHz. It is designed to replace the company's earlier (and larger) model ACMD-7401, currently the largest-selling duplexer for handsets in the US PCS market. The ACMD-7402 duplexer provides more than 54 dB rejection of transmit interference signals at its receiver input and more than 45 dB rejection of transmit-generated noise (receiver blocking) in the receive band. Receive band insertion loss is 3.8 dB or less (typically 2.8 dB) while transmit band insertion loss is 3.5 dB or less (and typically 2.1 dB). The receive port return loss is typically 12 dB in the receive band, while the transmit return loss is also rated at 12 dB in the transmit band. The duplexer is rated for +33 dBm (2 W) maximum RF input power to the transmit port.

The ACMD-7601 duplexer is designed for UMTS Band I transmit frequencies of 1920 to 1980 MHz and receiver frequencies of 2110 to 2170 MHz. This combination of bands is the most common version of the wideband-code-divisionmultiple-access (WCDMA) standard currently employed in Europe and Asia. The ACMD-7601 handles as much as +33 dBm power at its transmit port and features at least 45 dB receiver noise blocking with 2-dB maximum insertion loss in the receive band. The transmitter interference rejection is 51 dB or more, with transmission-band insertion loss of 1.6 dB or less. Specifications for both duplexers are for operating temperatures from -30 to +85C. P&A: $1.81 (ACMD-7402) and $1.54 (ACMD-7601)(100,000 qty.); stock.

Avago Technologies, 350 W. Trimble Rd., Bldg. 90, San Jose, CA 95131; (408) 435-7400, (877) 673-9442, Internet: www.avagotech.com.

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