X-Band Power and Linearity Performance of Compositionally Graded AlGaN Channel Transistors.

We report on the power and linearity performance of metal organic chemical vapor deposition grown AlGaN channel polarization-graded field-effect transistor (PolFET). The fabricated transistors with 3-D electron channels showed nearly flat transconductance profiles. Maximum ${f}_{T}$ and ${f}_{\text {max}}$ of 23 and 65 GHz were measured for 0.7- $\mu \text{m}$ gate-length transistors, corresponding to an ${f}_{T}$ - ${L}_{G}$ product of 16.2 GHz $\cdot \mu \text{m}$. Load-pull measurement at 10 GHz revealed a maximum output power of 2 W/mm with a maximum small signal gain of 16 dB. Two-tone measurement at 10 GHz showed an OIP3 of 33 dBm for 150- $\mu \text{m}$ device width and a corresponding linearity figure-of-merit OIP3/ $\text{P}_{\text {DC}}$ of 3.4 dB. These results suggest that PolFETs could be useful for high-frequency applications requiring high linearity. [ABSTRACT FROM AUTHOR]