A low phase noise Ku band push-push oscillator using slot ring resonator

In this paper, a push-push oscillator using a slot ring resonator based on "double-sided topology" is presented. This push-push oscillator is composed of two active sub-circuits arranged on the obverse side of substrate and a slot ring resonator arranged on the reverse side. By making the most of double-sided circuit topology, the ring resonator can be loosely coupled with two active sub-circuits, and be used as common resonator. A method of resonance stabilizing is proposed on the slot ring resonator to make the two active sub-circuits, and be used as a common resonator. A method of resonance stabilizing is proposed on the slot ring resonator to make the two active circuits oscillate in stable out of phase mode. Then the push-push oscillations can be exactly achieved, and satisfactory oscillating performances are obtained. At the desired second harmonic frequency (2f₀) of 16.0 GHz, the output power +10.0 dBm is measured with low phase noise of -121.3 dBc/Hz at 1 MHz offset frequency and -121.3 dBc/Hz at 100 KHz offset frequency. The measured suppression of the undesired signals such as the fundamental oscillating signal (f₀), the third harmonic signal (3f₀) and the fourth harmonic signal (f₀) are -37.5 dBc, -40.0 dBc and -42.2 dBc, respectively. To our knowledge, these results are comparable or better than the oscillators at X-band and Ku-band published in recent years.