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26 September 2007


Nitronex unveils GaN-on-Si broadband Doherty PA reference design for WiMAX

Nitronex of Durham, NC, USA has partnered with Prescient Wireless of Itasca, IL, USA (a supplier of RF products and design services to the wireless and avionics industries) to design a gallium nitride on silicon (GaN-on-Si) broadband Doherty power amplifier for WiMAX applications. Based on Nitronex’s existing NPT25015 power transistor, the design provides 6W of linear output power from 2.5GHz to 2.7GHz while achieving greater than 35% efficiency, 10dB gain, and less than 2.0% error vector magnitude (EVM) with digital pre-distortion.

“The inherent low output capacitance and high efficiency of GaN-on-Si are a natural fit for the Doherty architecture,” says marketing director Ray Crampton. “Carriers are asking for higher efficiency and broader bandwidth at the same time,” he adds. “We are currently collaborating with Prescient Wireless on a reference design based on our 125W NPT25100. Preliminary results show a similar level of performance is achievable at much higher output powers.”

Typical performance numbers were taken using a mobile WiMAX waveform defined as a single-carrier orthogonal frequency-division multiplexing access (OFDMA) 64-QAM with a 10MHz channel bandwidth. Output power of 6 Watts is achieved with a 9.5dB peak to average ratio (PAR) @ 0.01% probability on the CCDF (complementary cumulative distribution function) during the transmit portion of a 50% duty cycle true time delay signal.

The reference design consists of the schematic, bill of materials, circuit board layout files, detailed performance data, and documentation describing the design. Built and tested Doherty application boards are available.

Both the reference design and a design based on the 125W NPT25100 with preliminary results are on display at this week’s WiMAX World USA 2007 event in Chicago, IL (25-27 September).

See related items:

Nitronex’s 100W GaN-on-Si HEMT now production qualified

Nitronex launches 100W GaN-on-Si HEMT power transistor for WiMAX

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