This paper analyzes a high-frequency GaN-based boost converter considering an RL damper to mitigate critical oscillations. This work aims contributing with graphical correlations between power converter signals and root trajectories of the characteristic equation in the main oscillation loop. Results provide insights about the RL damper design to improve the power converter performance. A technical contribution shows that the highest efficiency depends on the lowest L and the highest R of the RL damper able to produce a damping operation. Additionally, simulation results demonstrate the improvement of the GaN-HEMT operation and reliability using an RL damper in a boost converter topology. An experimental GaN-based boost converter validates the developed study.