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Toshiba Corp. has developed a GaN power FET that far surpasses the operating performance of GaAs FETs widely used in base stations for terrestrial and satellite microwave communications. The new transistor achieves output power of 174 W at 6 GHz, the highest level of performance yet reported at this frequency.



Toshiba realized this breakthrough performance enhancement by optimizing the epitaxial layer and chip structures for 6 GHz-band operation and by adopting a four-chip combination structure to minimize heat build-up. The result is a GaN power FET with eight times the power density of a GaAs FET and the world's highest output power at the 6 GHz frequency level.



Having proven the design concept, Toshiba will continue to refine the technology, toward the target of sample releases next year. The new FET is expected to become a key component in microwave communications.



Ever-increasing communications flows are driving demand for higher output power in the amplifying devices used in base stations for terrestrial and satellite microwave communications. Until now, Toshiba has met this demand with GaAs-based FETs offering 90 W output power at 6 GHz frequency and 30 W at 14 GHz. However, heat dissipation is a critical issue with GaAs, to the point that the material is fast approaching the upper limits of its performance characteristics.



GaN shows great promise for application in amplifiers that support higher frequencies than the microwave band, since it offers higher saturation electron velocity, higher dielectric breakdown voltage and a higher operating temperature range than GaAs. Toshiba has focused on development of materials that can operate at a higher frequency than the C-band (4 GHz ¡V 8 GHz) and succeeded in demonstrating the world's highest power output by a GaN power FET at 6 GHz by structural optimization of the device. Toshiba is confident that it can achieve even higher output levels as it continues its development activities.