A Miniature YIG Tuned Oscillator/Frequency Divider Achieves Octave Tuning Bandwidth with Ultra Low Phase Noise in S, C, X and Ku Bands

Traditional YIG tuned oscillators use negative resistance type circuits and large magnetic structure to produce excellent phase noise with octave plus tuning ranges, but at the expense of size and weight. This paper describes a revolutionary approach to YIG tuned oscillator design which makes use of a unique combination of a miniaturized magnetic structure, and a GaAs HBT ring oscillator circuit topology, working through a YIG tuned filter to produce octave tuning ranges in X and Ku bands with phase noise less than -125 dBC per Hz at 100 KHz. To cover S and C bands, a digital IC frequency divider is used to divide the output frequency by an integer N. Phase noise is shown to improve by a factor 20Log(N). For N=4, and F0=12 GHz, at an output frequency of 3 GHz, the measured phase noise is -137 dBC per Hz at 100 KHz