Nujira cuts RF power consumption in handsets

Nujira has launched a handset version of its power-saving technology that it says can halve the energy consumption of the RF front end of an LTE terminal.

The part uses the Coolteq envelope-tracking technology that Nujira is already marketing to basestation and broadcast equipment makers. It works by adjusting the power supplied to the RF amplifier to match instantaneous power demand, rather than constantly supplying enough power to meet occasional peak demands. This also helps reduce the peak current consumption, which can be a limiting factor for handset and USB modem designs.

Nujira will use the upcoming Mobile World Congress in Barcelona to show the chip to handset makers, RF power amplifier makers, and chipset vendors as a development platform and proof of concept. It hopes to license its technology for integration into other vendors' chipsets and RF power amplifier modules, rather than trying to make and sell parts itself. The company says one of the top five handset makers has already bought the development platform.

"The prospect of selling silicon like this to the top five handset makers as a small Cambridge fabless semiconductor company seems remote," said Julian Hildersley, VP handset products and strategy, Nujira.

Nujira is also trying to broaden the appeal of its envelope-tracking technology by making alliances with other vendors. Its Coolteq.h family of envelope-tracking modules now directly interfaces with Texas Instruments’ GC5322 and GC5325 digital predistortion transmit processors and development boards, through a newly defined envelope-tracking interface.

The company wants to make it easier to sell envelope-tracking technology to PA and basestation equipment makers by defining a common standard for the envelope modulation interface. To this end it will make its interface definition available to others.

"I'd hope people would realise that [power modulation] is not simple technology to develop so we'll have a lot of design slots, so it would make sense for others to work to our standard," said Tim Haynes, CEO.

Nujira has also worked with TriQuint Semiconductor to integrate the Nujira technology into a new TriQuint PA, to create what they claim is the world’s most efficient 2.1GHz basestation PA. The design achieves over 55 per cent efficiency at 2.1GHz.

Nujira has been working with RF Micro Devices to develop what it claims is the world’s most efficient broadband PA design for 4G basestations, integrating an RFMD gallium nitride amplifier with Nujira’s envelope-tracking ethnology. The design transmits over a 728 to 960 MHz band with more than 50 per cent efficiency, covering seven of the frequency bands defined for LTE by 3GPP. RFMD is also developing other broadband PAs that will enable it to address the whole cellular spectrum, from 700MHz to 2600MHz with three broadband PAs, allowing wireless infrastructure vendors to develop a single, highly-efficient multimode, broadband RF front end that can be deployed to meet various transmission standards anywhere in the world.

Ultimately Nujira believes it should be possible to serve the entire cellular spectrum with just two PAs, rather than up to seven, as some current designs demand.

Tim Haynes, Nujira CEO, said: “Infrastructure vendors are facing a portfolio management crisis, with more than 60 product variants needed to cover all worldwide frequency bands, cellular standards, and power levels. Even if they had the specialist engineering resources available to develop each product, the development costs and timescales would be prohibitive."

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