Peregrine Semiconductor's CMOS power amplifier promises GaAs-level performance in 4G phones. Will handset manufacturers now shift to silicon, asks Compound Semiconductor.

CMOS designs: Peregrine Semiconductor is confident its UltraCMOS technologies will displace GaAs systems in top tier smartphones.

In early February, this year, Peregrine Semiconductor unveiled its UltraCMOS Global 1, described as the industry's first reconfigurable RF front-end system. Comprising the company's prized RF switchers and tuners, the system also houses a multimode, multiband power amplifier, which Peregrine describes as the first CMOS PA to match the  performance of the GaAs equivalent.

Following in the footsteps of Qualcomm's CMOS front end module, the RF360, released in February 2013, Peregrine has designed the system to challenge GaAs incumbents in 4G markets. However, Duncan Pilgrim, Director of Strategic and Technical Marketing at Peregrine claims this system is different; it really performs.

"When Qualcomm released the RF360 we thought this is great, it validates what we've been doing for the last fifteen years; integrating the front-end," he says. "But the big difference for us is there's no trade-off in performance."

"[The power-added efficiency of] GaAs PAs has traditionally been at least 10 percentage points higher than CMOS PAs... but our technology allows us to meet the same performance as GaAs for WCDMA and LTE standards," he adds. "There is no trade-off in battery consumption, network capacity; we truly believe we have hit the same performances as the GaAs equivalent."

According to Peregrine figures, the power added efficiency (PAE) of the UltraCMOS Global 1 PA, using a WCDMA waveform at an adjacent channel leakage ratio of -38 dBc, approaches 50%, on par with today's cutting-edge GaAs PAs. What's more, the PA is said to maintain the GaAs-equivalent PAE for LTE waveforms with varying resource-block allocations. And this is without performance enhancements from envelope tracking or digital predistortion, although the system supports all envelope tracking modulators.



"Since 2006, we've worked on creating the most efficient amplifiers on a CMOS process, We've been working closely with Soitec and Global Foundries... and we have around 73 patents associated with the RF front end," says Pilgrim. "We've really been trying to tie in all of this with design techniques as well, and this has enabled the improvements in efficiency that we've now got."

Systems have been sampled and Peregrine is currently working on platform integration. Pilgrim reckons this will be completed within 12 months, so production will then start early next year. But will the handset manufacturers buy?

Pilgrim thinks so. Performance aside, he highlights how the reconfigurable system will allow manufacturers, busy grappling with LTE handsets to support more than 40 frequency bands, to save time and money by creating a single-SKU design that operates across global markets. "Look at the iPhone, the China Mobile rollout brought a 6th model and the only difference in all those phones was the RF front end," he says. "If you provide a front end that supports all the different regions... it simplifies the whole supply chain."

Still, the release of Qualcomm's CMOS RF360 has hardly displaced GaAs PAs from RF front end markets, and some industry pundits are now questioning the need for the much-touted global SKU.

"This idea, that one part serves all bands and all regions, may not be as universally accepted as once thought," says Eric Higham, Director of GaAs and Compound Semiconductor Technologies, at Strategy Analytics. "Frequency allocation is regional and there is no single frequency used globally. We hear that with only one PA part number, any change requires requalification on a global, rather than regional basis and this will slow time to market and increase cost."

Still Higham is keenly watching market developments. As he highlights, CMOS PAs have been capturing market share in lower tier terminals for some time, but a shift in focus to LTE - from both Qualcomm and Peregrine - has taken the industry by surprise.

"The integration levels of Qualcomm's RF360 and the performance claims of Peregrine's Global 1 solution are impressive," he says. "Both companies represent formidable foes for the handset PA portion of the GaAs industry."

Indeed, Pilgrim describes the Global 1 system as a "game changer" that will accelerate a market transition from GaAs to silicon PAs.



Duncan Pilgrim of Peregrine Semiconductor: "We truly believe we have hit the same performances as the GaAs equivalent."

"Back in 2011 we saw a real transition point for switches from GaAs to silicon on insulator. We've now hit that point again with power amplifiers," he says. "In the next few years you are going to see a dramatic increase in the number of CMOS solution hitting the market... it wouldn't surprise me if we saw some consolidation [amongst GaAs device manufacturers] in the industry."

Higham concurs that manufacturers of CMOS PAs will now capture market share from GaAs players, with Qualcomm and Peregrine being well-positioned to act. But he also emphasises how many GaAs device makers focus on markets beyond the handset sector that are likely to remain GaAs-dominated for the foreseeable future.

And as he asserts, Skyworks, RFMD and Avago all recently acquired CMOS PA design capabilities in preparation for a possible industry transition from GaAs to silicon PAs. "Peregrine has been the driving force behind the conversion of handset switches from GaAs to silicon, so is a recognised leader in this area," he adds. "But a challenge that the company now faces is, how long will it take for them to be recognised as an amplifier manufacturer? The performance of Global 1 will go a long way to minimise this concern but it will need to be addressed."