Optimal design and implementation of high-efficiency and high-power-density CLL resonant converter with gallium nitride transistor and integrated magnetics is presented. The matrix transformer and resonant inductor are integrated into a magnetic core. The core loss after integration is reduced by flux cancellation and verified by finite element analysis (FEA) tools. A symmetrical PCB winding layout is presented for a 7:2 transformer turns ratio. To reduce the common mode noise caused by the interlayer capacitance of the PCB winding, half of the shielding is used as the primary winding. Finally, a 1.2-MHz 750-W 270-V/48-V CLL converter prototype is demonstrated to verify the effectiveness of the magnetic integration structure with PCB-winding. The peak efficiency of the prototype is 96.6% and the power density is 720 W/in³.