Study of Low Noise with High Linearity AlGaN/GaN HEMTs by Optimizing Γ-Gate Structure for Ka-Band Applications

Abstract

This paper investigates the device noise and linearity of an AlGaN/GaN HEMT with an optimized Γ-Gate structure for Ka-band applications. The Γ-Gate was used to provide low gate resistance for the device by increasing the gate cross-section and acting as a gate field plate to achieve a flat transconductance (Gm) profile. The device’s Gm profile was analyzed under different gate positions, including at the center or close to the source. Under different bias conditions, we performed the optimization of the Γ-gate head length (Lhead). The results show that an excellent minimum noise figure (NFmin) for the device can be achieved when the Γ-gate is positioned close to the source with an optimum Lhead. Finally, the NFmin improved from 1.9 dB to 1.59 dB and the third-order intercept point (OIP3) value improved from 27.7 dBm to 31.1 dBm when the source-drain distance (LSD) was reduced from 2.5 μ m to 2 μ m . It was demonstrated that the optimized Γ-Gate design has the potential to attain the device with low noise and high linearity.