2 February 2010


Nujira uses RFMD’s GaN to create 50%-efficient 700–1000MHz PA

At the GSMA Mobile World Congress in Barcelona, Spain (15–18 February), Nujira Ltd of Cambridge, UK and RF Micro Devices Inc of Greensboro, NC, USA are to demonstrate what is claimed to be world’s most efficient broadband power amplifier (PA) design for 4G base-stations. The design integrates Nujira’s Coolteq.h envelope tracking power modulators with RFMD’s new RFG1M family of gallium nitride (GaN) amplifiers (specifically, the RFG1M09180 180W GaN broadband power transistor).

Using just one RFG1M device with a Coolteq.h module, the RF front end transmits over a 728–960MHz band with more than 50% efficiency, covering seven of the frequency bands defined for LTE (long-term evolution) by 3GPP. The results of this broadband GaN-based PA platform surpass competitive wideband Doherty LDMOS solutions, it is claimed. Also, using future GaN devices currently in development at RFMD, the firms expect to cover the full range of the cellular frequency band (700–2600MHz) with just 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.

“Expect to see GaN, coupled with envelope tracking, in many new RRH designs,” comments Lance Wilson, research director, RF Components & Systems, with market analysts ABI Research, which issued the report ‘Remote Radio Heads’ in December. “With a GaN/envelope tracking amplifier promising such high-efficiency operation, the Doherty circuit configuration can be disposed of and bandwidth will increase incrementally,” he adds.

“In partnership with RFMD, we have created a PA which covers the entire 700–1000MHz band without compromising on efficiency,” says Nujira’s CEO Tim Haynes. “Coolteq modulators feature the only technology that can deliver this level of efficiency across such a broad bandwidth, extending the software-defined radio approach to the high-value power amplifier,” he adds.

“We’re delighted to be collaborating with Nujira in setting new standards for energy-efficient transmission performance based on our new RFG1M products and on our state-of-the-art GaN process,” says Bob Van Buskirk, president of RFMD’s Multi-Market Products Group (MPG), who envisions the combination of envelope tracking and RFMD’s GaN technology changing the way base stations are designed.

The joint design addresses a major issue in the 4G cellular base-station market, says Haynes. “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, with each and every variant costing hundreds of thousands of dollars to design, test, type approve, and qualify for production,” he adds. “We have delivered a high-efficiency, broadband PA platform which can be deployed across multiple product variants, reducing time-to-market, development costs, and the cost of ownership associated with inventory management.”

See related item:

TriQuint and Nujira create record-efficiency 2.1GHz base-station PA

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