GaN supplier Nitronex has partnered with Prescient Wireless to design a GaN-on-Si broadband Doherty power amplifier for WiMAX applications. Using NPT25015 power transistor, the design provides 6 W of linear output power from 2.5 to 2.7 GHz while achieving >35% efficiency, 10 dB gain, and <2.0% EVM with digital pre-distortion.

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“The inherent low output capacitance and high efficiency of GaN-on-Si are a natural fit for the Doherty architecture. Carriers are asking for higher efficiency and broader bandwidth at the same time. It is exciting to achieve industry leading results that directly apply to their problems,” said Ray Crampton, marketing director at Nitronex. “We are currently collaborating with Prescient Wireless on a reference design based on our 125 W 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 OFDMA 64-QAM ¾ with a 10 MHz channel bandwidth. Six Watts of output power is achieved with a 9.5 dB PAR @ 0.01% probability on the CCDF during the transmit portion of a 50% duty cycle TTD signal, according to Nitronex.

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 from the supplier.