Ultra-Linear and High-Efficiency GaN Technology for 5G and Beyond

Realizing the full potential of mm-Wave 5G and beyond communication systems will require transistors with higher linearity and efficiency than current technology options. While GaN HEMTs offer excellent power density, their limited linearity and efficiency, especially under complex modulations, compromises overall system performance and requires substantial digital pre-distortion compensation as well as substantial power back-off. Here, we report the large-signal, two-tone linearity of graded-channel GaN HEMTs at 30 GHz, and compare their performance to that of conventional AlGaN/GaN HEMTs. In class AB bias, a two-tone P AE of 62% was obtained experimentally, which is a state-of-the-art result. We find that ~3 dB back-off from peak P AE is sufficient to achieve a carrier to third-order intermodulation (C/IM3) ratio of 30 dBc. Further, the efficiency under this back-off condition provides an associated P AE of 55% at 30 GHz. Hence, the GaN HEMTs are promising for mm-wave linear and efficient amplifiers, including 5G applications.