Properties of synchronization in the systems of non-identical coupled   van der Pol and van der Pol - Duffing oscillators. Broadband synchronization
  The particular properties of dynamics are discussed for the dissipatively coupled van der Pol oscillators, non-identical in values of parameters controlling the Hopf bifurcation. Possibility of a special synchronization regime in an infinitively long band between oscillation death and quasiperiodic areas is shown for such system. Features of the bifurcation picture are discussed for different values of the control parameters and for the case of additional Duffing-type nonlinearity. Analysis of the abridged equations is presented. 
Alexander P. Kuznetsov, Julia P. Roman