Differential resonant ring oscillator utilizing magnetically tuned YIG resonators to achieve ultra low phase noise and multi-octave electronic tuning in microwave frequencies

A tunable yttrium iron garnet (YIG) resonant oscillator circuit with a closed-loop ring oscillator topology, said circuit comprising:

• a magnet field tuned YIG sphere positioned in the near field of a ring magnet and magnetic field focuser and magnetically coupled to at least two conductive loops, including a first and a second conductive loop, each of said conductive loops proximate said YIG sphere;
• first and second amplifiers operating together as a differential pair, each configured for a gain greater than one, arranged in a feedback loop configuration, wherein the direct current ground terminal of each of said amplifiers is connected directly to circuit ground, and further wherein the output terminal of said first amplifier is coupled to the output terminal of said second amplifier through said first conductive loop, and the input terminal of said first amplifier is coupled to the input terminal of a said second amplifier through said second conductive loop;
• a direct current source for providing operating and bias voltages to both of said first and second amplifiers;
• and
• wherein said resonant oscillator circuit oscillates at a frequency that is dependent on the resonant frequency of said YIG sphere, and said resonant frequency can be adjusted by varying said magnetic field.