Quite a few questions about the chipset used in the new 4G phones - what bands does it support, how's it work, more.
The attached whitepaper from Qualcom should help to answer some of your questions!
Snapdragon S4 class incorporates the latest in mobile architecture design and technology to address the demands for intelligent connectivity, high performance and energy efficiency.
• First on 28nm process technology: Snapdragon S4 processors are the first mobile processors to be manufactured using the latest 28nm process technology that provides inherent advantages in frequency scaling, power consumption and size reduction.
• First Fully Integrated 3G/4G: The S4 class includes the industry’s first fully integrated LTE world mode/multimode modem.
• Uses ARM® instruction set, software and eco-system: Snapdragon S4 processors are the first processors in the industry to be designed specifically for advanced process technology and uses the ARM instruction set architecture (ISA). Snapdragon S4 processors are complete solutions that provide a superior balance of performance and power efficiency delivering:
• Superior CPU performance: Multicore CPUs with a frequency range of 1.5Ghz to 2.5Ghz per core and supporting asynchronous symmetric multiprocessing (aSMP) for the optimal balance of performance and power efficiency.
• Superior modem performance: The industry’s first fully integrated LTE world/multimode modem with support for the widest range of frequencies and bands—including full multimode support for existing standards such as EV-DO and HSPA.
• Superior graphics performance: High performance programmable Adreno GPUs for the highest quality video and console quality gaming.
• Superior power efficiency: Tight integration of best in class components and use of highly efficient, low power engines such as Qualcomm’s fully programmable Hexagon DSPs result in a highly power efficient system. Connectivity options also include integrated GPS, Bluetooth, WiFi, and FM.
Download the attached whitepaper for more details about the Snapdragon S4 chipset used in the HTC Evo 4G LTE and more Sprint 4G LTE phones!
While the chipset supports everthing from DC to Light, the HTC Evo 4G LTE supports 800/1900 3G CDMA (EVDO) and 1900 LTE out of the box, according to the HTC Evo 4G LTE Specs page. Not particularly world friendly. Worldwide LTE roaming is going to be 'interesting' - every carrier is deploying on different, non-compatible frequencies right now. Until 3GPP or ITU or someone mandates a standard like GSM, you won't see a lot of cross-carrier interoperability.