Intel estimates that there are 1 billion subscribers to social networking services worldwide, and that every day 175 million people access these services' websites (from a presentation given at the 2008 Intel Developer Forum). Increasingly, subscribers depend on handheld Internet devices for connecting to their social networks. Yet social networks are only one of many types of applications for these systems: they include information, communication, entertainment, and productivity.
In particular, digital communication and entertainment applications will give users a graphics-rich and video-intensive experience, and will depend on a mix of several wireless communication capabilities such as 3G, WiMAX, WiFi, GPS, Bluetooth, and mobile TV. All of these applications require high-speed data transfers and/or high screen resolutions, and will use considerable amounts of battery power in mobile Internet devices (MIDs), netbooks, and smart phones.
The design targets of MIDs include a single-cell battery, as well as a high-efficiency power system that allows long battery life and low standby power, while simultaneously being able to respond quickly to wake-up commands. Processor manufacturers for all handheld Internet devices—including Intel for MIDs, ultra-mobile PCs, and netbooks, and Marvell, TI, and Freescale for smart phones—are struggling to reduce both operating and idle power consumption of their processor platforms. Intel, which has supplied a majority of the processors used in these handheld devices, announced its goals for the next-generation Moorestown (Lincroft) MID processor platform compared to first-generation MIDs based on its Atom (Menlow) platform. These goals are to reduce operating power by just over 2.5X and reduce idle power consumption by 5X.
Power consumed by the MID's display constitutes a large percentage of the overall platform power. Like everything else in a MID, therefore, the display electronics must operate on low standby power and low operating voltage while transferring high-resolution graphics at high speeds.
Defining the problem: Display and display interface technologies
Over the last few years, the display technology used in mobile handsets has shifted from simple LCDs to full-color VGA resolution (640 by 480 pixels) LCDs. This change has enabled high-end mobile handsets to provide multiple features, including media players, digital cameras, and handheld Internet appliances. These smart phones often employ thin-film transistor (TFT) LCDs with display resolutions up to wide VGA (WVGA), or 800 by 480 pixels, and color depths of 24 bits/pixel.
Several challenges come with these high-resolution displays. They require at least a 24-bit data bus and four control signals. As a result, power management, electromagnetic interference (EMI), and flex cable reliability have become challenging issues for designs that use older parallel internal interfaces. Therefore, many designers have shifted from older, slower, cumbersome parallel RGB or CPU interfaces to high-speed serial interfaces for LCDs on mobile handsets. The shift to serial interfaces also means fewer EMI problems as serial lines reduce problems such as crosstalk. It also means a lower power consumption, higher mechanical reliability, and a more easily scalable architecture.
