Electrothermal and Linearity Analysis of GaAs-Based Nano HEMT

An MBE-grown AlGaAs/GaAs nano HEMT is electrothermally analyzed in this work, emphasizing its linearity performance over a broad temperature range $\left(-40^{\circ} \mathrm{C}\right.$ to $\left.150^{\circ} \mathrm{C}\right)$. Key nonlinear performance metrics, such as $\text{VIP}_{2}, \text{VIP}_{3}, \text{IIP}_{3}, 1$ $\text{dB} \text{CP}, \text{IMD}_{3}, \text{HD}_{2}, \text{HD}_{3}$, and THD, are extracted and examined through a combination of DC and RF measurements. The findings show changes in the ideal gate bias conditions and a consistent deterioration of linearity metrics with temperature. Notably, biasing conditions that provide thermally stable performance are identified by the zero-temperature coefficient (ZTC) points found in $\text{VIP}_{3}, ~\mathrm{g}_{\mathrm{m} 3}, \text{IIP}_{3}$, and $1 ~\text{dB}-\text{CP}$. The study also emphasizes how $\mathrm{g}_{\mathrm{m}}, \mathrm{g}_{\mathrm{m} 2}$, and $\mathrm{g}_{\mathrm{m} 3}$ change with temperature, significantly impacting harmonic generation. These results provide information about the temperature-dependent distortion mechanisms in GaAs HEMTs and valuable recommendations for creating thermally robust, high-linearity RF circuits.