Startup Runs MCU on 5 MicroW

Article By : Rick Merritt

Startup Eta Compute will demo at Hot Chips a Cortex-M3 running at 5 microW, targeting SoCs run on energy harvesters for the Internet of Things.

SAN JOSE, Calif. – A startup will demo at Hot Chips next week an ARM Cortex-M3 SoC doing useful work while consuming five microwatts. The Dial architecture from Eta Compute represents a new low for the annual event traditionally focused on high-performance processors.
Eta claims it can enable significantly lower power microcontrollers than are currently available using asynchronous circuits that can operate down to 0.25V. “We think we can make a dent in the way embedded systems are built,” said Paul Washkewicz, one of three co-founders and the vice president of marketing and sales at Eta.

The startup will discuss its technology at an event packed with papers describing the latest high-end server processors, graphics accelerators and FPGAs. In a sign of temporary slump in enthusiasm for IoT in semiconductors, the startup’s paper is one of the few on the topic. However, the event includes as many as eight talks on machine learning amid the current excitement over AI.

Eta's 90nm chip can multiplex between an A/D converter, DSP and Cortex-M3 cores while dissipating less than 50 microwatts. It has a lower power version working in silicon built in a 55nm process.

The designs aim to enable simple nodes on the Internet of Things such as Bluetooth beacons and LoRa end points running off energy harvesters such as small solar panels. The 90nm design runs the M3 core at a data rate of up to 200 kHz, powered by a solar cell with fluorescent lighting. Washkewicz argues getting rid of batteries will be useful for many kinds of IoT deployments.

The three Eta founders came from Inphi, a startup that established a successful business building components for high-end optical networks. For their latest startup, they developed a methodology for designing asynchronous circuits using Tempus and Innovus tools from Cadence.

“Most people have tried to use asynchronous technology to compete with Intel or Nvidia at the high end, routing gigahertz clock trees or designing deep-learning accelerators. We went the other way and rode voltage levels down,” said Washkewicz.


*Eta used Cadence tools to create a design flow for building asynchronous circuits. *

Their Dial architecture uses a novel handshake to wake up circuits resting at power levels below 0.3V. It quickly turns on devices without the set up and wait times associated with synchronous circuits.

Plenty of microcontrollers support data rates as low as 100 kHz. Only a few such as startup Ambiq can support circuits running as low as 0.9V. Washkewicz claims Eta’s 0.25V technology enables a five-fold improvement in MIPS/Watt compared to today’s MCUs.
The capability is driving interest among a handful of early adopters. “One customer we are working with has hundreds of microcontroller SKUs and it wants to get an advantage over the other guys,” Washkewicz said.

“Right now we are licensing IP. If the right opportunity comes along well do chips, but right now we see enough interest in IP to fund further development,” he said.

Eta’s road map includes a mix of new IP blocks such as temperature sensors and power management blocks and ports to additional processes that may include 40 and 28nm nodes.

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