While Texas Instruments, with its “LoCosto" wireless handset chip, opted to use digital CMOS technology to integrate the RF and baseband chips on a single die, Freescale Semiconductor is headed in a much different direction.
By using its redistributed chip packaging (RCP) technology (see yesterday’s article and a PDF presentation on WeSRCH's paper section), Freescale will package five or more wireless ICs into a single module.
Sandeep Chennakeshu, general manager of Freescale’s wireless IC group, said TI’s single-chip radio-plus-baseband solution is not optimal, particularly as CMOS scaling proceeds and “the parasitics become very difficult at those advanced nodes.”
With $2.14 billion in wireless chip revenues last year (roughly a third of Freescale), the decision to optimize a multi-chip solution with RCP packaging is radically different than the integrate-as-much-as-possible approach taken by TI, Infineon, and others.
Instead of a monolithic CMOS die, Freescale will package a now-sampling RF transceiver chip (based on a 90-nm RF-CMOS process with two extra masks compared with digital CMOS), with a digital baseband chip (fabbed in 65-nm low-power CMOS). The RCP module also will contain a GaAs-based power amplifier IC, a power management/user interface chip made in 130-nm SmartMOS10 BiCMOS process, as well as memories and discretes.
By using RCP packaging, Freescale eliminates fanouts and can shrink the module by about half, compared with BGA packaging, Chennakeshu said.
“Our next-generation RF will not require any filtering. By using RCP we can deliver the right architecture for each segment of the market. Integrating everything into a single chip is not the way to go for these emerging standards,” said Chennakeshu.
Jim Mielke, technology and strategy director at Freescale’s wireless and mobile systems group, said TI’s strategy would be well suited to the low end of the handset chipset market, where every nickel counts. However, TI’s LoCosto approach depends on getting high yields, which he said is difficult when RF functions are fabbed on a fairly large die.
“By using RCP, we can get to a lower BOM and have more flexibility in what we do at the different tiers of the market,” Mielke said. For example, Freescale’s RF solution offers a band selection feature, with four wideband CDMA and four GSM/Edge channels supported simultaneously.
About weQuest: weQuest's are written by G Dan Hutcheson, his career spans more than thirty years, in which he became a well-known as a visionary for helping companies make businesses out of technology. This includes hundreds of successful programs involving product development, positioning, and launch in Semiconductor, Technology, Medicine, Energy, Business, High Tech, Enviorntment, Electronics, healthcare and Business devisions.