  We propose a new graphene-based THz circulator. It consists of a circular
graphene resonator and three graphene nanoribbon waveguides of W-geometry
placed on a dilectric substrate. Surface plasmon-polariton waves propagate in
the waveguides. The nanoribbon excites in the resonator dipole resonance.
Nonreciprocity of the device is defined by nonsymmetry of the conductivity
tensor of the magnetized graphene. The circulator with the central frequency
7.5 THz has the bandwidth 4.25\% for isolation -15 dB, insertion loss -2.5 dB.
Applied DC magnetic field is 0.56T and Fermi energy of graphene
$\epsilon_F=0.15$eV. The Fermi energy allows one to control dynamically the
circulator responses.
