The paper presents the results of numerical simulation of a miniature dual bean monotron with three-gap resonator, made by technology of integrated circuits. Was studied the stability of this device to different oscillation modes. It is shown that when working on main mode output power of the device on the 2,2 GHz is in the range from 150 to 350 watts with the change cathode voltage from 2 to 3,5 kV. The maximum value of technical efficiency of the device was 22 % at minimum a single beam current of 0,15 A. The proposed scheme of the device when using the field emission cathodes can also be realized in the millimeter wavelengths.