Harvesting cellphone RF energy to boost battery life: Page 2 of 3

October 21, 2016 //By Nick Flaherty
A wireless charging startup is looking to boost battery life in mobile phones and tablets by harvesting the RF energy from their radio links. Nick Flaherty talks to Marc Chen, CTO of Radient Micro-Tech (Fremont, CA).

The solution is largely software based. “We don’t need a dedicated IC for our technology to be implemented as there is already an RF IC module and power management in the devices so all we need to add is an RF to DC converter which is just a few transistors and everything is in the device already so the additional cost is negligible.”

The advantage for the phone maker is reducing the size of the battery to give more space in the design or increasing the manufacturing tolerances to reduce costs. “If you can reduce the battery size by 30% that’s a cost saving and gives more space to do things,” he said.

However, having an extra antenna on the back of a phone can change the performance of the device, and he is well aware of this. “When the cellphone is transmitting only about 10% of the energy gets to the cell tower – the direction of the cell tower is generally not known but there are things we can do to determine whether our receiver is effecting the link,” he said. “One of the things we are doing is working with the algorithms in the transmitter to determine whether it is affecting the transmission.

This is a challenge for all phone makers. “Even the Qi charger or even the camera will affect the transmitter and have to be placed very carefully so we place the antenna close but not too close, so maybe we are collecting 20 to 25% of the energy and even that is enough to make a difference.”

The company is looking to license the technology to phone makers but also to wireless charger makers and even phone case suppliers, although this is not an immediate route to market