Ultra low phase noise sapphire-SiGe HBT oscillator

A state of the art C-band oscillator is presented. It is based on a high Q WGM sapphire resonator combined with a low residual phase noise SiGe HBT amplifier. A two oscillator experiment performed on this system has revealed a phase noise level of -133 dBc/Hz at 1 kHz offset from the 4.85 GHz carrier, which is the best published phase noise result for a single loop, free running microwave oscillator.