Abstract: A microstrip stabilized quantum well resonance-tunneling generator which generates electromagnetic waves for millimeter and submillimeter wavelength range is provided The generator includes a resonant tunneling semiconductor quantum well diode, and a microstrip resonator. The resonant tunneling diode, the microstrip resonator and interconnecting lines and junctions are fabricated as a monolithic integrated device on a common substrate. As a result, the monolithic integrated device provides the expansion of the operation frequency range toward the terahertz region as a result of reduction of the parasitic inductance as well as of minimizing the other parasitic parameters of the electric circuitry connecting the resonant tunneling diode and resonator.