Simon Maurice Wood

Design of GaN HEMT Transistor Based Amplifiers for 5 - 6 GHz WiMAX Applications

2.5 and 5 Watt average power (15 and 30 Watt peak power) GaN HEMT amplifiers for WiMAX signal protocols have been designed and fabricated for use in the 5.5 to 5.8 GHz band. The 2.5 Watt PA produces 11 dB of gain and the 5 Watt PA produces 10 dB of gain with EVMs less than 2.5% at the respective average power with drain efficiencies greater than 26% at average power. A design methodology for optimizing linear performance is described for these two transistors and resultant amplifiers.

Reliability comparison of 28 V–50 V GaN-on-SiC S-band and X-band technologies

Abstract This paper discusses the reliability performance of Wolfspeed GaN/AlGaN high electron mobility transistor (HEMT) MMIC released process technologies, fabricated on 100 mm high purity semi-insulating (HPSI) 4H-SiC substrates. The intrinsic reliability performances of the 28 V and 40 V technologies, with 400 nm and 250 nm gate length, have been characterized with DC accelerated life test (DC-ALT), for which ohmic contact inter-diffusion is the wear-out mechanism, and is accelerated by temperature and current. The intrinsic reliability performance of the 50 V technologies, with 400 nm gate length, have been characterized with RF-ALT, for which source-connected second field plate void coalescence is the wear-out mechanism which is accelerated by temperature. In spite of the differences in the accelerated test methodologies and wear-out mechanisms, all of the Wolfspeed GaN-on-SiC technologies demonstrate high and similar predicted lifetimes at their respective maximum recommended operating conditions. The reliability performance is supported with successful technology qualifications with zero failures, and volume manufacturing with a demonstrated low field failure rate.