News

# RF-based Wireless Charging from 2 Meters? New Team-up Combines RF Energy Harvesting and RF WPT

June 09, 2021 by Kate Smith

## Could we be charging our devices from two meters away? Atmosic and Energous Corporation claim we can—and that the key is RF.

Wireless charging has been a fiddly technology for some. (Remember that time Apple tried and then gave up?) Wireless charging for mobile devices commonly relies on short-range inductive coupling using wire coil design (often Litz wire) that sometimes requires a bit of realigning to work.

Two companies focused on innovative uses of RF (radio frequency), Atmosic and Energous Corporation, are combining efforts to provide more options for RF wireless charging or WPT (wireless power transfer) at a distance.

In an announcement released today, the two companies claimed an industry first: "first interoperability energy harvesting" for wireless charging that allows for charging from up to two meters away.

##### Image from Energous Corporation.

The duo of companies asserts that this "industry-first interoperability" is crucial for scalable wireless charging adoption.

### Atmosic's M3 SoC (The "RF Energy Harvesting" Part)

Atmosic is a fabless semiconductor company that has made waves with its low-power Bluetooth technology, specifically for IoT devices. It was founded in 2016 by a veritable gang of former Atheros founders (turned Qualcomm execs when Atheros was acquired in 2011), including two Stanford electrical engineering Ph.D.s.

One of Atmosic's core concepts is the "forever battery," the idea that devices can use the same batteries forever without needing to be replaced because they are used very minimally. Atmosic also asserts that the use of devices like the M3 may make batteries obsolete entirely by harvesting energy from various sources, including:

• ambient light
• RF and thermal
• mechanical

What Atmosic brings to the table for this interoperability announcement is the M3 SoC chipset, which is based on Bluetooth LE 5.0, supports on-chip RF energy harvesting (plus all other types of energy harvesting listed above), and utilizes a 16 MHz Arm Cortex M0 CPU.

##### The block diagram for the M3. Image from Atmosic

In 2019, the M3 was recognized as a CES 2020 Innovation Honoree in the Embedded category. The SoC was highlighted for its Bluetooth 5/BLE (Bluetooth Low Energy) RF radio combined with an Arm Cortex M0 processor and the above-mentioned RF energy harvester. In particular, it features what Atmosic calls "on-demand wake-up," which uses listening devices—one for perceiving incoming transmissions ("radio consciousness") and a second that is activated once incoming signals are detected.

### Energous WattUp Transceiver ICs (The "RF-based WPT" Part)

Energous Corporation, for their part, has developed a reputation around their alternative to the traditional coil- and silicon-based design for wireless power transfer. Their part in this Atmosic interoperability equation is RF-based wireless charging technology, specifically the playfully named WattUp transmitter family. According to their website, their approach sidesteps issues such as foreign object detection and thermal management associated with coil-based WPT.

In late 2016, Energous announced a $10 million partnership with Dialog Semiconductor, an initiative that received an additional$15 million in investment from Dialog Semiconductor in mid-2017. Out of this partnership, the two companies joined forces to produce the WattUp IC family, which includes transmitters and receivers.

##### Promotional image of the WattUp DA4100 near field transmitter IC from 2017. Image from Dialog Semiconductor.

In 2017, Energous also claimed an industry first in receiving the first certification under Part 18 of the FCC's guidelines regarding "Power-at-a-Distance" wireless charging. This FCC guideline deals with questions of proximity, load modulation, and RF exposure for devices that don't use RF for communication and operate in the ISM (industrial, scientific and medical) band.

By combining their work in this space with Atmosic's RF energy harvesting, the two companies are aiming at the heart of two difficult (and sometimes contentious) topics: "battery-free" devices and reliable at-a-distance WPT.

What WPT systems interest you the most? What do you see as the future of WPT in the next year, five years, or ten years? Share your thoughts in the comments below.