FBAR Filter, Duplexer Isolate PCS Signals

Jan. 26, 1998
This novel yet practical semiconductor technology was used to produce a high-performance, low-cost duplexer and transmit filter for PCS handsets and data cards.

Filters, once a challenge for semiconductor manufacturers to fabricate, are now being produced in the millions by high-volume batch processes. The Semico nductor Products Group of Agilent Technologies (Palo Alto, CA), for example, has already shipped more than 20 million of its thin-film bulk-acoustic-resonator (FBAR) duplexers. The components, which now ship at a rate of 2 million per month, are designed into nine of the top ten CDMA phone manufacturers' US PCS band handsets. Adding strength to its position, the company announced the availability of a new FBAR PCS duplexer, the model ACMD-7401, and a new FBAR PCS-band transmit filter, the model ACPF-7002.

The FBAR technology is a silicon-based semiconductor process that can be readily integrated into front-end modules and other silicon-based semiconductor solutions. FBAR components are environmentally sealed by the firm's innovative Microcap packaging, which involves bonding a cap wafer onto the FBAR wafer.

The ACMD-7401 duplexer, for example, measures just 5 × 5 mm with a maximum height of 1.4 mm—about one-tenth the size of competing solutions. Designed for PCS handsets and data cards, it has a receive band of 1930 to 1990 MHz and transmit band of 1850 to 1910 MHz. Although 66-percent smaller than the company's first-generation FBAR duplexer (model HPMD-7904), the duplexer exhibits 2.2 dB typical receive-band insertion loss and 1.8 dB typical transmit band insertion loss. The duplexer achieves 44 dB receiver noise blocking and 54 dB typical transmit interferer blocking at power levels to +30 dBm. Its low temperature coefficient of 25 PPM/°C ensures stable performance with temperature.

The ACPF-7002 PCS transmit filter measures just 1.6 × 2.0 mm, but rivals the performance of much larger split-band SAW transmit filters with switches. The FBAR transmit filter features 2.5 dB typical insertion loss over the PCS transmit band of 1850 to 1910 MHz with typically 37 dB rejection (minimum of 33 dB) from 1930 to 1990 MHz. The tiny filter, with minimum ripple of 2.5 dB and typical return loss of 11 dB from 1850 to 1910 MHz, handles power levels to +20 dBm. P&A: $2.45 (ACMD-7401, 100,000 qty) and $0.54 (ACPF-7002, 100,000 qty.); stock. Agilent Technologies, Semiconductor Products Group, 5301 Stevens Creek Blvd., Santa Clara, CA 95051; (800) 235-0312, e-mail: semiconduc [email protected], Internet: www.semiconductor.agilent.com.

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