The　emerging　gallium　nitride-based　semiconductor　device　due　to　lower　switching　loss　and　smaller　package　size　enables　multi-phase　point-of-load　(POL)　converters　toward　higher　power　density　and　efficiency　in　data　centers.　The　discrete　inductors　occupy　a　large　proportion　of　the　size　and　are　a　bottleneck　for　further　increasing　power　density.　Inverse　coupled　inductor　technology　is　a　promising　solution　for　core　size　reduction　for　multi-phase　interleaving　POL　converters.　In　this　paper,　a　novel　magnetic　core　structure　of　fully　symmetric　four-phase　inverse　coupled　inductors　are　presented,　which　overcomes　the　limitation　of　asymmetrical　inductor　parameters.　The　proposed　magnetic　core　structure　has　the　advantages　of　larger　inductance　value,　smaller　size　and　fully　symmetric　inductor　parameters.　A　comprehensive　analysis　of　basic　magnetic　circuit　model,　derivation　of　inductance　value　and　design　of　magnetic　core　by　Maxwell　3-D　are　discussed.　A　108W,　12-1.8V,　GaN-based　prototype　of　four-phase　interleaving　POL　converter　utilizing　the　proposed　magnetic　core　is　built　and　tested.　The　experimental　results　demonstrate　that　the　converter　has　lower　output　current　ripples　and　symmetrical　inductor　current　waveforms.　©　2021　IEEE.