For most people, a wearable is synonymous with a smartwatch or a fitness monitor, devices that have grown over the years into mature products. While there continues to be room for innovation in each of these device categories, both have “crossed the chasm” – a marketing concept first coined by Geoffrey A. Moore in 1991. In simple terms, this concept refers to products that are now popular not only among early adopters but are also increasingly being adopted by pragmatists as well.
While smartwatches and fitness monitors continue to grab the consumer mindshare, a few other innovations in the wearable space have gained significant traction. Some of the most popular use cases for these devices include:
- Recording and Social Engagement: Leaders in this market produce high-quality cameras that are used in a variety of sports such as surfing, skiing, and skydiving. These cameras come with a multitude of accessories that allow a user to attach the camera on various surfaces and at interesting angles, making it possible to take pictures and videos previously not possible without professional equipment.
- Productivity Enhancement: These are devices that can be used in various commercial applications in which context-driven information on a heads-up display can enhance productivity, efficiency, and quality of workflow (like in medical operations, machine diagnostics and repairs, etc.).
- Training: Fitness bands and smartwatches are the primary devices used by many athletes to track and improve performance; however, recently, technology has been integrated into accessories that we already wear and own. This opens a world of transformative experiences which enrich the entire athletic experience, providing data that can increase motivation, enhance training, and ultimately improve performance. In order to bring wearable devices closer to being seamless, unobtrusive, everyday accessories, some new products try to incorporate functionality without compromising design and personal preferences. Some of the headphones and earphones on the market today not only serve as a channel for the delivery of music, but some of these also come with other smart technologies that allow a user to track heart rate, blood pressure, oxygen saturation levels, ECG/EKG, and temperature.
- Gaming, Entertainment, and Virtual Reality: Virtual reality, in simple terms, can be referred to as immersive multimedia that simulates physical presence in a place, either in the real world or the imagined world, and lets a user interact in that world. The simulated environment can be similar to the real world to create a life-like experience (for example, simulations exist for a pilot, combat training, and videogames). Consumer-targeted virtual reality devices, such as headsets, are on the rise. These devices may primarily be offered as a gaming device, but they may also find use cases in non-gaming applications as well, such as media, social, and industrial/professional applications.
In general, the more complex the application, the more sophisticated the wearable product’s architecture. Products that have some form of audio or video tend to have higher-end processors and larger density memory, while those that are used primarily for tracking purposes in sports or in training (those with a small display or no display at all) tend to have a more simple architecture. For the sake of summarizing architectures, we can look at them as three separate categories: wearable sports/action cameras, head-mounted displays/smart glasses, and smart training accessories (earphones, fabrics, etc.). The architecture inside the devices within each category is mostly similar.
Wearable Sports/Action Cameras: According to a teardown performed by iFixit, GoPro’s Hero3 camera contains an Ambarella A770 system on a chip (SOC), an ams AS3713 power management unit with backlight driver, USB and Bluetooth controllers from NXP and Qualcomm Atheros, respectively, and a multichip package (MCP) memory of 1Gb NAND and 4GB LPDDR3 (low power DDR3) from ChipSiP. Measuring 15 x 15mm in size, the SOC from Ambarella enables 1080p60 H.264 performance. Being a portable device, the low-power feature is of great importance in the design of such wearables. This further justifies the use of LPDDR3 in this type of design, which consumes low power and offers high performance (bandwidth, frequency). Most of the other action/sports cameras have a similar architecture in terms of processor and component selection. The main decision driver in this device category is highest performance at lowest power.
Head-Mounted Displays/Smart Glasses: Smart glasses are slightly different in their architecture and design. The fact that this device is worn on the face/head limits the size of the product, which in turn limits the size of each of its components. According to TechInsights, the original Google Glass contains an OMAP4430 processor from Texas Instruments. This processor is a based on a dual-core ARM Cortex-A9 MPCore processor, and is capable of speeds greater than 1GHz per core. It contains a high-performance, programmable graphics engine and image signal processor for high video and imaging performance. While low power is still key in such a design, the added requirement for small physical size makes this architecture more complex. The OMAP4430 processor measures about 12 x 12mm and has a fine pitch of 0.4mm. Working in conjunction with this SOC are various sensors and connectivity modules (GPS, Wifi, Bluetooth, accelerometer, compass and gyroscope) and memory (16GB of NAND and 8Gb of LPDDR2). Other smart glasses and virtual reality applications have similar requirements (performance) and limitations (size, power), and hence, levitate toward a similar architecture for their design.
Smart Training Accessories: Other wearables catering to less-intense applications tend to have a much simpler architecture. For example, headphones that can measure heart and respiration rate, blood pressure, oxygen levels, ECG/EKG, and body temperature contain not only a microcontroller but also high-end sensors (gyroscope, accelerometer, magnetometer) and other testing tools (pulse oximetry, optical touch IC, Bluetooth controller and digital micro-electro-mechanical systems [MEMS] microphone). Although some of these devices have storage capacity, not all have additional sensors and microcontrollers, most use the internal memory of the microcontroller. The relatively tiny sizes of the sensors and microcontrollers (typically 5 x 5mm or 7 x 7mm) allow for much smaller form factor for the end products.
Discrete Components: Most wearable devices in the monitoring category act as accessories to a smartphone. The focus in these devices is on size and battery life efficiency, and because they are tethered to a smartphone, they don’t need to store as much local data. Even a day’s worth of health and fitness measurements can be minuscule relative to the size of audio and video files. With physical space in wearables at a premium, memory (NOR flash) capacity, die size, and low power consumption is a better fit for many of these devices. NOR devices in the 1-256Mb capacity range are available in small footprints (such as a wafer-level chip-scale package (CSP), 2 x 3mm dual-flat no-leads (DFN), and industry standard small outline integrated circuit (SOICx), depending on density). Micron offers NOR as part of its extensive portfolio of memory products. Micron continues to innovate in the NOR space, particularly in serial NOR, which has recently reached performance levels that can be comparable or better than traditional parallel NOR. In addition, serial NOR has the added advantage of fewer pins and simpler design—both of which are of importance in the design of a wearable product. Another interesting memory product that is a good fit in this space is serial peripheral interface (SPI) NAND. As memory requirements scale up to support additional sophistication in wearable product design, designers may likely feel the need for additional storage at a price that keeps the overall BOM cost low. SPI NAND offers the benefits of serial NOR, such as low pin count and smaller package size, but comes in larger densities (1Gb to 8Gb) and at price points that can be lower than serial NOR for the same densities. Micron today offers three different package types – DFN, SOIC16, and ball grid array (BGA). SPI NAND offers a transitional path for wearable designs that are maturing and needing additional memory to supports its needs.
Multi-Chip Packages (MCPs): Generally, MCPs refer to a package with two or more different types of technologies. NOR flash can be stacked in an MCP with pseudo-static RAM (PSRAM) to further conserve space. For example, a 64Mb NOR flash and 32Mb PSRAM-based MCP is only 4 x 6 mm, and higher-density MCPs with up to 512Mb NOR flash and 128Mb PSRAM are only 8 x 8 mm. MCPs involving the combination of LPDDRx and NAND result in a slightly larger foot print due to the larger size of the individual dies, but this combination provides the performance required by higher-end wearable devices like cameras and smartglasses. One way to conserve space in these MCPs is to use package-on-package (POP) versions, which are packages that stack on top of the SOC, further reducing the overall real estate required to fit all the components on the printed circuit board (PCB). In addition, the proximity of the memory to the SOC allows for short interconnects (lesser data integrity issues) and enables accelerated time-to-market though rapid integration of modules.
A volatile memory (usually LPDDRx) can also be put together with an e.MMC, which gives the added benefit of faster time to market. The e.MMC takes care of a lot of the NAND management, allowing a user to focus their time on other parts of the product design. Such MCPs that contain e.MMC as one of its components are referred to as e.MCP (e.MMC-based MCP).
Today, Micron has a broad portfolio of MCPs and offers small packages with unique combinations of nonvolatile memory (NAND, NOR, e.MMC) as well as RAM (LPDRAM, PSRAM).
Wearables is an exciting market that is evolving at a remarkable pace. It is also a broad and somewhat fragmented market, with each of its various categories serving different use cases. As the concept of a connected world takes shape and develops into reality, wearables will allow humans to interact not only with each other but also with the world around them. As the acceptance for wearables grows, we will see more optimized and mature designs in the near future. As a leading innovator in semiconductors, Micron will continue its efforts to support and enable wearables as a product category with memory products that will not only differentiate the wearable product, but will also enhance the user experience.