Abstract:It is assumed that the effect of superlattice sawtooth shaped channel on particles is equivalent to the periodic field of a similar shape. Under the framework of classical mechanics and small amplitude approximation, the motion equation of particles is reduced to Duffing equation with a dual frequency excitation by using the sine squared potential. Due to the third order nonlinearity, there are main resonance, sub resonance, combination resonance,etc in the system. Multi frequency resonance was analyzed by perturbation method, and the stability and the critical conditions of the system were discussed. The results show that the system is stable when the nonlinear strength is less than the critical intensity.