The investigation of high-frequency and high linear, high electron mobility transistor (HEMT) Al0.3Ga0.7N/GaN HEMT is designed for low-noise amplifier front-end (LNA) for the next-generation wireless communication applications, such as the internet of things (IoT) and internet of everything (IoE). A thick barrier of 25 nm with a high aluminium composition of 30% is used to improve the linearity and RF efficiency. This device epitaxial can be used to reduce the defect caused by traps. Al0.3Ga0.7N/GaN HEMT device achieved a high drain current of 4.17 A/mm with a 1 μm gate length. The designed device is modelled at different gate-to-drain distances (LGD) to investigate the breakdown voltages. Interestingly, devices with less LGD produced high breakdown voltages. The amplitude of the higher-order transconductance derivatives obtained is of the order of 2.5 which is threefold the conventional transconductance (gm1). An accurate sub-threshold swing (82.28 mV) is generated for smooth switching transitions (device ON to OFF and vice-versa). Surface traps and interface traps destroy the output characteristics for certain gate swing voltages. Large thickness surface passivation is incorporated to reduce the vertical gate leakage in the drain bias-affected region. A high cut-off frequency (fT) of 588 GHz is achieved in the proposed model. A large broadband frequency range and exceptional linear performance handling capabilities are used as a transmit/receive module (TRM) for high-power radar and space applications.