A differential resonant ring oscillator (“DRRO*) circuit using a ring oscillator topology to electronically tune the oscillator over multi-octave bandwidths. The oscillator tuning is substantially linear, because the oscillator frequency is related to the magnetic tuning of a YIG sphere, which has a resonant frequency equal to a fundamental constant multiplied by the DC magnetic field. The simple circuit topology uses half turn or multiple half turn loops magnetic coupling methods connecting a differential pair of amplifiers into a feedback loop configuration having a four port YIG tuned filter, thus creating a closed loop ring oscillator. The oscillator may use SiGe bipolar junction transistor technology and amplifiers employing heterojunction bipolar transistor technology SiGe is the preferred transitor material as it keeps the transistor's 1/f noise to an absolute minimum in order to achieve minimum RF phase noise.