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23 April 2008


Nitronex and Nujira collaborate on high-efficiency WiMAX PAs

At this week’s Next Generation Networks & Basestations conference in Bath, UK, gallium nitride on silicon (GaN-on-Si) RF power transistor manufacturer Nitronex Corp of Durham, NC, USA said that it is creating a power amplifier reference design for WiMAX base-stations delivering over 45% efficiency by collaborating with RF power efficiency specialist Nujira Ltd of Cambridge, UK. This is being done by using Nujira’s high-accuracy tracking (HAT) modulator technology to dynamically control the power supply to the GaN device in line with the transmission performance required.

Nujira’s aim is to improve the energy efficiency of 3G and 4G cellular network base-stations and DVB digital broadcast transmitters by reducing the amount of waste energy dissipated as heat in the RF power amplifier circuit.

Picture: Nitronex's NPT25100 GaN-on-Si RF power transistor.

Using a four-channel WCDMA waveform, the firms have been able to realize over 44dBm of linear power with 45% efficiency at a linearity of -55dBC using conventional DPD (digital pre-distortion) techniques. The results were achieved using production-ready devices from both companies, which greatly increases customers’ confidence in adopting the approach, according to Nitronex’s VP of marketing & sales Chris Rauh. This same solution demonstrated its flexibility by achieving 43.2dBm of linear power with 43% efficiency under a demanding WiMAX waveform with 20MHz video bandwidth and 8.2dB peak/average ratio (PAR).

“Nitronex believes that GaN devices will most clearly establish their value when combined with advanced power amplifier techniques such as Nujira’s HAT technology,” says Rauh.

“Nujira HAT envelope tracking technology can greatly enhance the efficiency of power amplifiers, allowing the creation of modules that deliver both high energy efficiency over a broad frequency spectrum and flexibility,” says Nujira’s VP strategy & marketing Julian Hildersley. “The same Power Modulator module can equally well be applied to WiMAX, WCDMA or even DVB and other transmission,” he adds. “Our reference design work with Nitronex very effectively demonstrates how well our technology works in a real circuit.”

Samples of Nitronex’s NPT25100, simulation models and standard evaluation boards are available now. Samples of the amplifier pallet optimized for high-accuracy tracking integrated with Nujira’s power modulator enabling customers to develop amplifiers using their own DPD systems will be available in third-quarter 2008.

See related items:

Nitronex and Merrimac to develop highly integrated PAs for wireless infrastructure

Nitronex develops 45W GaN-on-Si HEMT for high-PAR power amplifiers at 2.5 and 3.5GHz

Search: Nitronex GaN WiMAX base-stations