High-efficiency low-phase-noise 79-GHz Gunn oscillator module

A high-oscillation-efficiency low-phase-noise 79 GHz Gunn oscillator module has been developed. The Gunn diode chip, which was fabricated on a GaAs substrate, includes an AlGaAs/GaAs electron launcher and a graded transition layer, which reduce the operation voltage. The oscillator uses planar reflector circuits at its anode and cathode to reduce the phase noise. The oscillator module produces an output power of 14.0 dBm (24.7 mW) at 78.9 GHz using a 0.95 W DC power input, and achieves a high oscillation efficiency of 2.5%. Its best phase noise characteristic under free-run oscillation is −107 dBc/Hz at 79 GHz with 1 MHz offset. The temperature dependencies of the oscillation frequency and power were also examined and the overall performance was found to be sufficient for use in 79-GHz radar/sensor applications.