This study considers electrical parameters of AlGaN/GaN high electron mobility transistor (HEMT) with the recessed gate and un-doped region (URG-HEMT) in the barrier layer. We have investigated the main electrical factors such as the lateral electric field, breakdown voltage ($V_{B}$), drain current ($I_{D}$), threshold voltage ($V_{T}$), output conductance ($g_{o}$) and gate capacitance ($C_{g}$). Simulation findings compare these parameters in the single heterostructure (SH-HEMT), recessed gate (RG-HEMT) and the proposed (URG-HEMT) structures. Regarding the simulation outcomes, the maximum lateral field in the URG is less than those in the SH and RG-HEMTs. This improves the breakdown voltage of the suggested device up to 160 V, while the breakdown voltage in the SH and RG transistors is about 90 V. Therefore, breakdown voltage of the reported device is about 80% larger than that of the other transistors. Also, undoped region in the novel transistor reduces the output conductance and gate-to-drain capacitance. But, the recessed gate and undoped regions in the URG structure decrease in 2-DEG electron density and then reduce drain current.