Phase Noise Improvement of a Fourth-Harmonic Push-Push Oscillator Using a Ring Resonator With Additional Microstrip-Line Resonators

This paper presents a new Push-Push oscillator with low phase noise and simple configuration. Two sub-oscillators are integrated with a microstrip-ring resonator, an output circuit and two additional microstrip-line resonators to enhance the stability of the resonant field in the ring resonator. As the output circuit is loosely coupled to the ring resonator, the fourth-harmonic signal is effectively obtained without disturbing the resonant field. The proposed oscillator improved the phase noise by around 2 dB from a Push-Push oscillator not using microstrip-line resonators.