Qualcomm® RF360™ is in the news again. First to launch was the envelope tracker on the Samsung GALAXY Note 3, then the antenna matching tuner on the Nokia Lumia 1520, and now the QFE23xx—an integrated multimode multiband power amplifier (MMMB PA) and antenna switch—has launched on the ZTE Grand S II LTE smartphone! This is the last chipset in the Qualcomm RF360 family to launch but plays a key role in enabling the RF360 vision of simplifying the RF front-end and making possible a single LTE design capable of global roaming.
What is the QFE23xx? It is in fact two chips—QFE2320, the CMOS MMMB PA with integrated antenna switch, and QFE2340, high band CMOS PA with integrated transmit/receive mode switch. The high band QFE2340 is the first commercial wafer-level nano-scale package MMMB PA in the mobile industry and introduces a new RF architecture for LTE TDD with its integrated transmit/receive mode switching capability.
Less is more
What this means is that QFE23xx pack in more RF front-end functionality than before into fewer RF components. This helps achieve significant area savings without sacrificing performance by integrating more cellular modes and RF bands into the QFE23xx power amplifiers thereby freeing up PCB board area to accommodate an even greater total number of bands. In this particular implementation, the ZTE Grand S2 supports an impressive 17 total number of bands covering 4G LTE (TDD and FDD), 3G (WCDMA and TD-SCDMA) and 2G GSM.
I like to think of the QFE23xx chips as the ultimate space saver, just like the coffee machine at my workplace which can serve 30+ drinks from one compact machine. The machine has three modes, coffee drinks, gourmet selections, and hot beverages, plus a nice touch interface that allows the user to go within each mode to select a drink of his or her choice.
Now if you think of the three modes as 2G, 3G, and 4G cellular technologies, of the drinks available in each mode as the different frequency bands each technology is compatible with, and of the touch interface as a switch that selects across different modes and bands, you can see how the QFE23xx chips are the multimode, multiband RF front-end equivalent of the coffee machine.
Smaller, flexible, global RF platform
All this functionality leads to simplified routing, ease of RF design and eventually compact device form factors for end users. By maximizing re-use of RF circuitry, the QFE23xx minimizes BOM, reduce engineering effort, and enable a flexible RF platform that can be used by OEMs to launch different band configurations across the globe using a single PCB design.
The QFE23xx also works with the QFE11xx (envelope tracking chips) and the QFE15xx (antenna matching tuners) to deliver the greater benefits of RF360: higher throughputs, lower power consumption and thermals, and extended antenna operational range in thinner form factors.
This successful commercialization of QFE2320 and QFE2340 chips is a major breakthrough in mobile RF and represents another big step forward for Qualcomm RF360. As I start to reflect upon how far the Qualcomm RF360 front-end solution has come in a short period of time, now is perhaps a good time for me to take a trip back to the coffee machine…