Ambiq Aims to Enable Wearables a 10-Fold Reduction in Power Consumption

By: Jonah McLeod, Silicon Valley Blogger

The wearable device is in its infancy as a new product category, with only a few years of product shipments. But the market is on track for significant growth. According to the recently published data from ABI Research in Oyster Bay, New York, the global market for smart wearables is forecast to grow from 90 million units this year to 164 million units next year. The forecast includes wearable cameras, smart glass, smart watches, health-monitoring devices, activity trackers, motion trackers, and smart clothing.

As with any infant market, the initial products are crude by comparison to later models to come.  Contrast the Sony Walkman with the MP3 player that replaced it years later eliminating many of the older units drawbacks—size, weight, and power consumption. One drawback of today’s wearable that everyone can point to is battery life. For example, Jawbone boasts that it had doubled the battery life of its UP24 wristband from one week to two weeks. While that’s a considerable improvement, it’s insignificant when contrasted to the battery life of two to five years for a Movado quartz watch.

Ambiq Micro is an Austin, Texas-based fabless semiconductor start-up formed in 2010 that wants to make the considerable improvement in battery life that will bring it closer to what consumers expect from quartz watches, garage door openers, and auto key fobs. Ambiq Vice President of Marketing, Mike Salas says the company has developed new technology that will provide a 10-fold improvement in battery life.  “And we’ve developed and shipped a real-time clock chip that lives up to the claim,” he asserts.  Ambiq’s larger goal is to create an ultra low-power microcontroller-based infrastructure that leverages their patented technology to provide 10-fold improvement in battery life for wearables as well as to devices comprising the Internet-of-Things.

What’s making all of this possible is sub-threshold voltage technology that Ambiq’s co-founders Dennis Sylvester, David Blaauw, and Ambiq CTO and VP of Engineering Scott Hanson, Ph.D. developed at the University of Michigan beginning in 2004.  “Today standard logic CMOS circuits switch transistors between 0v and 1.8v,” Salas explains. “Ambiq’s sub-threshold voltage technology switches standard logic CMOS transistors between 0v and 0.5v. And the technology leverages the leakage current in logic CMOS to accomplish the switching. It’s not possible to build a GHz microcontroller with this technology, but in the wearables and IoT market, power trumps performance.”

To reliably switch transistors at 0.5v is no mean feat. “There is always noise in the sub-threshold voltage domains, which are insignificant if the transistor is switching between 0v and 1.8v,” Salas says. “But with a swing of only 0.5v, noise becomes something that could be misconstrued for signal.  In addition, for any CMOS process node there is a center that designers develop around, but the process can drift thus creating the need to compensate in the low-voltage domain. The same holds true for temperature ranging from -40 to 85 degrees C. Ambiq’s patented technology includes adaptable circuitry that adjusts and accounts for this noise, temperature drift and process variability.”

To achieve their larger goal of more power-efficient system designs, the company is beginning to partner with sensor and radio chip suppliers, display and battery manufacturers, software vendors, cloud suppliers and app makers as well as tooling companies and automatic test equipment vendors. “The goal is to create a low-power infrastructure that produces the most energy efficient solution for the OEM,” Salas explains. “For example, the partnership with a tooling vendor might develop models of the discharge characteristics of various batteries or energy harvesting solution to determine power consumption in an Ambiq-based system with different radios, sensors, and displays. The partnership with the ATE vendor would create testing methods to effectively test logic circuits switching at much lower 0.5v. With software vendors the partnership might include determining how best to develop software to leverage the low-power profile of the Ambiq hardware it’s executing on.”

Using their sub-threshold voltage technology, the company is designing a microcontroller chip around an ARM licensed CPU core, which they will sell through the established semiconductor component channels—direct to major OEMs and through distributors to smaller OEMs. Ambiq’s low-threshold voltage microcontroller by itself will deliver considerable power savings to a wearable or IoT OEM. But involving an infrastructure of suppliers able to exploit the low-voltage computing element will deliver even greater power savings to the OEM. Ambiq plans to begin shipping their ARM-base microcontroller toward the end of the year. Already wearable and IoT OEMs are lining up to sample the low-power compute engine using an Ambiq supplied FPGA platform.

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