Powering innovation

Not that long ago, competition in the microprocessor world centred on x86 designs for desktop pcs and risc devices for workstations. "In the 1990s, [CPU design] was all about performance – nobody cared about power consumption or how much it cost," said Linley Gwennap, principal analyst of The Linley Group. But, as the market matured, x86 players either left the market or were acquired, leaving Intel and AMD to fight it out. Today, it is the mobile computing market that is fiercely contested, especially processors for smartphones and sub notebooks – a computer class known variously as mobile internet devices or netbooks. "With mobile processors, it is not just the processor, but also 3d graphics, audio and video processing and cellular, all designed with an incredibly low power budget and constrained cost," said Gwennap. For Gwennap, mobile processors are now driving semiconductor innovation. "Mobile processors are the hardest design task to take on – the same performance as a pc crammed onto one chip," he said. Qualcomm's Snapdragon is one such device and is already used to power Google's high profile Nexus One smartphone. Based on the ARM Cortex-A8 instruction set, Qualcomm has several Snapdragon ics and plans to adopt the design across more of its product families. Snapdragon's origins date back five years when Qualcomm brought onboard a low power PowerPC processor design team released by IBM. "We hired the team intact," said Mark Frankel, vice president of product management at Qualcomm's CDMA Technologies division. The team began designing its ARM based core with a target clock speed of at least 1GHz. Five years on, several Snapdragon designs exist. The first, now shipping in smartphone products, is the 65nm 1GHz QSD8250/ 8650. "The QSD8250 and 8650 is the same silicon," said Frankel. "The difference is the firmware: the 8250 is UMTS only, while the 8650 is multimode and supports CDMA-2000." Two follow on 45nm Snapdragon designs have been detailed: the QSD8650A, clocked at 1.3GHz, and the dual core QSD8672, clocked at up to 1.5GHz. Qualcomm owns an ARM architectural license, such that while Snapdragon is code compatible with ARM's Cortex-A8, the company has freedom to design its own hardware. The result is an ARM7 compatible superscalar processor with a 128bit single instruction, multiple data (SIMD) engine, dubbed VeNum, instead of ARM's 64bit NEON. "We can dispatch instructions with a greater throughput than a typical ARM, and we control the [memory] caches and where we put them," said Frankel. "Not only do we have control of the process and transistor mix, but also the [technology's] creative design." In addition to the SIMD engine, Snapdragon includes a dsp and a graphics unit. The QSD8250's 600MHz dsp is Qualcomm's own design and performs mainly video processing. The device can encode and decode video at a 720p rate and includes dedicated hardware blocks. The faster QSD8672 is able to process video at 1080p. Given the dedicated dsp, why is the SIMD engine – ideal for multimedia processing – needed? The answer is to run multimedia codecs, such as flash, written by third parties. In contrast, the dsp, with its own microcode, was never designed to be programmed by Snapdragon based product developers, says Frankel. The 2d/3d graphics engine is the result of Qualcomm's acquisition of the assets of an ATI unit, whose graphics core Qualcomm had licensed previously. "The 3d graphics is extremely important it is the first [product] impression a user gets," said Frankel. The 3d graphics performance of the QSD8650 is 22million triangle/s and 133m 3d pixel/s. It also supports displays of up to wxga (1366 x 768). The QSD8672 extends performance to 80m triangle/s and more than 500m 3d pixel/s. Display capability is extended to wsxga (1440 x 900). As for Snapdragon's integrated wireless modem, the QSD8650/A supports UMTS, including the high speed packet access standard (HSPA), as well as CDMA-2000, while the QSD8762 also supports the faster data rate HSPA+. The 3G modem is a core advantage of Qualcomm's integrated device. "As a leader in 3G cellular, if designers choose the Snapdragon, they know they are getting a solid 3G baseband used around the world," said Gwennap. To constrain the Snapdragon's power consumption – and hence prolong a mobile device's battery operating life – functional blocks are clocked independently. "The power can also be switched down within a clock cycle and when you need processing, it can be switched on almost instantly," said Frankel. The 65nm 1GHz QSD8650 device consumes 0.5W and has a standby rating of 10mW. The 45nm process reduces the power consumption to 0.35W for the QSD8650A. Qualcomm claims 15 manufacturers are now developing 40 designs based on the Snapdragon. First to be announced was the Toshiba TG01 smartphone. Since then, other smartphone product launches include such firms as HTC, Acer, Sony Xperia and LG. In January, Qualcomm announced that Lenovo is developing several designs to be launched by US operator AT&T. This will be followed by launches in China and Europe. Qualcomm is also working with HP on a Snapdragon based Android device. Meanwhile, the Google Nexus One handset is the fastest clocked smartphone on the market. Qualcomm's mix of design wins spans leading smartphone and smartbook makers. But, by integrated a powerful cpu with a cellular modem, the design is confined to applications that require both functions. "It is not the device for navigation devices or media players, unless mobile functionality is also needed," said Gwennap. This is in contrast with the likes of Texas Instruments, whose OMAP processor is targeted at several products. "The good news for Qualcomm is that cellular is popping up in a lot of places, such as e-books, while a lot of netbooks are sold with cellular functionality included," said Gwennap. Snapdragon faces stiff competition from the likes of Marvell and Freescale (see NE, Feb 23, 2009), as well as from Intel and Nvidia. While ARM's Cortex-A8 may not be clocked at 1GHz, ARM continues to invest heavily in its architecture and has announced the Cortex-A9 cpu, which has architectural enhancements such as instruction reordering. This will give a processing edge for the same clock speed as the Snapdragon. According to Linley Group, the Cortex-A9 cpu will ship in Nvidia's Tegra 250 in the second quarter of 2010. Tegra 250 contains two Cortex-A9 CPUs; each running at up to 1GHz. Texas Instruments' OMAP4 also uses ARM's Cortex-A9 and will ship later this year. Vague definitions There is a lack of rigour when it comes to describing mobile computing devices; even experts agree that definitions are 'slippery'. * A netbook is a portable device with a full keyboard and a display typically ranging from 7 to 10in. Connectivity is important, as the device is not specified to host the applications found on notebooks. * The mobile internet device fits between a netbook and smartphone. But, with a 4 to 5in screen, is often too big to fit into a pocket.