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 differential amplifiers, each configured for a gain greater than one, arranged in a feedback loop configuration, wherein the emitters of both of said differential amplifiers are connected directly to circuit ground, and further wherein the collector of said first differential amplifier is coupled to the collector of said second differential amplifier through said first conductive loop, and the base of said first differential amplifier is coupled to the base of a said second differential amplifier through said second conductive loop;
• a first direct current source for providing a collector voltage to the collectors of both of said first and second differential amplifiers;
• and
• a second direct current source for providing a bias voltage to the bases of both of said first and second differential amplifiers;
• 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.