GaN HEMT Performance - Measurements and Simulations of a 3.6 mm Device from Cree

The premise of GaN HEMT devices to offer superior power amplification performance in microwave frequencies lead to an extensive research in this field, and to numerous publications emphasizing individual performance records such as, current & power densities, linearity and break down voltage. The performance of these, primarily experimental devices, is often reported in the terms of their intended applications, offering either the saturated output power, or 3dB compressed output power, or OFDM and CDMA waveform-specific output power, making the comparison among the devices, and a comparison with other technologies such as LDMOS & GaAs rather difficult. The authors are engaged in the design of a wideband (10:1 BW) 50W @ 1dB compression point linear power amplifier operating up to 2GHz. As a step in this process we determine the performance of an actual, 3.6 mm periphery, pre- production GaN HEMT from CREE. The device performance is simulated using CREE model, and it is compared with the measurements we have taken, both reported in this paper. The results obtained exhibit good convergence with the model, and are presented using the more common performance parameters such as power and efficiency at 1dB compression point, and the linearity in terms of IP3. Index Terms — GaN, HEMT, wide band gap, power amplifiers.