Cellphones integrate RF to cut costs

Lowering cellphone costs by integrating radio components was a running theme at the International Solid-State Circuits Conference.

Broadcom, Infineon and Texas Instruments detailed solutions for pulling more of the RF work into 2.5G digital devices, typically integrated with baseband processors. Separately, Broadcom and the former Analog Devices cellular RF group, now owned by Taiwan's MediaTek, described ways to purge passives from 3G phone designs.

Accessing emerging markets
"There is 100 percent saturation in mature cellphone markets, so continued growth depends on accessing emerging markets, where you need something on the order of a $20 phone. That requires integration," said Bob Staszewski, a member of the technical staff at TI. He described a 90nm, 24mm2 baseband with an integrated quadband radio that is shipping now. The device still requires a 2W power amp, battery charger and SAW filters. Its baseband includes a C54x DSP and an ARM 7 processor running at 104MHz.


Infineon went a step further: A chip now shipping integrates a 250nm power-management device on a substrate with the 130nm baseband and digital radio by means of a system-in-package design. The baseband includes a 260MHz ARM and 178MHz TeakLite DSP.

Tossing the SAW
For Tony Montalvo, a design center director for ADI who co-chaired the session on cellular transceivers, "the more pressing issue is removing external passives. In W-CDMA , quadband designs can require up to seven SAW filters."

MediaTek described a triband W-CDMA/HSDPA transceiver that eliminated six SAW filters and three low-noise amps while cutting the cost of calibrating the radio to meet 3G cellular standards.

Broadcom described a 65nm W-CDMA transmitter that uses a feedback filter to suppress receiver noise while consuming just 65mW. The design eliminated the need for a SAW filter.

- Rick Merritt
EE Times