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Tiny antennas allow wireless charging of multiple devices

Posted: 07 Dec 2015     Print Version  Bookmark and Share

Keywords:Si-Ware Systems  Ossia  WiFi  CPU  wireless charging 

Cairo-based Si-Ware Systems (SWS) and Ossia Inc. have developed the Cota wireless charging technology that moves away from coil-based systems to simultaneously serve up to eight devices at a distance of about 9.14m using 2.4GHz multi-path radio frequency.

Global revenues for wireless power receivers and transmitters will grow to more than $1.7 billion this year, according to IHS. A 2014 report put the market at $8.5 billion by 2018.

Like RF startup Energous, Ossia and SWS envision a charging technology that mimics WiFi, automatically connecting devices to power without the need for charging mats. The Cota system includes a scalable receiver and transmitter with between 1,000 and 8,000 tiny antennas.

SWS' SWS1420 receiver chip can retrieve up to 6W and will be embedded in portable devices and eventually be put in batteries. The receiver transmits a synchronised beacon to the transmitter to locate and focus power, while also performing power management in a small, though unspecified footprint. The receiver refreshes its location 100 times per second for environmental adjustment.

Cota receiver architecture

Cota receiver architecture (Source: Si-Ware Systems/Ossia)

The SWS1410 MIMO transmitter chip can deliver more than 10W with support for up to four antennas, a central CPU that can store location data for different clients and on-chip RAM. Abid Hussein, chief commercialisation officer at Ossia, which developed Cota's antenna technology, made a distinction between his technology and beam forming.

Each antenna emits a few milliwatts of ambient power he said, then uses massive multi-path technology to process a receiver's signal and send power to a chip or chips. Ossia and SWS will demonstrate a consumer-scale personal area transmitter at CES in January.

Cota transmitter

Cota transmitter (Source: Si-Ware Systems/Ossia)

The current transmitter supports up to eight simultaneous clients. Its ASIC can determine which device requires the most power or which has the lowest battery. Smartphones or wearables that want to use Cota will still require an additional communications chipset from Si-Ware. Hussein expects that chip to cost less than $1.

Do efficiency or coils matter?

Measuring energy efficiency among the various methods of wireless charging can be a difficult task, with different definitions of efficiency among different standards bodies and no standard test. Ossia and Si-Ware didn't have any hard numbers on system efficiency, but said the goal was to be comparable to a wall charger. Efficiency is also affected by the number of devices being charged at once and distance from the transmitter.

The value in Cota isn't in charging efficiency as much as the ability to roam and charge simultaneously, Hussein noted.

Coil-based charging systems from Qi and the newly formed AirFuel Alliance are getting the most traction in the consumer market, but Hussein said he does not see those systems as competitors. Rather, deployment and creation of networks is the biggest challenge for Cota.

The first-generation chips are made in CMOS technology from GlobalFoundries. The transmitter will sample in 1Q16 and the receiver ASIC will sample in Q2. Hussein said Ossia will announce "a major partnership" at CES.

- Jessica Lipsky
  EE Times Europe

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