This paper proposes a gate driver IC for GaN-based synchronous buck converter with a double-sided adaptive dead-time generator (DTG) to improve the converter efficiency with conventional fixed or single-sided DTG. It contains two main sub-blocks such as the phase error detector (PED) and the coarse/fine controllers. Applying the edge detection principle, the proposed dead-time control can minimize the dead-time and reverse conduction loss at both edges of the switching voltage, Vx, of a 1MHz 12V to 5V buck converter using e-mode GaN devices for 0.2 to 1A load current range. The designed IC is fabricated with TSMC 0.18um HVG2 process. According to the post-simulation, the minimum dead time at 1A of load current is 28ps. Compared with a fixed DTG and single-sided DTG, efficiency is improved by 10% and 6%, respectively.