A unilaterally coupled push-push oscillator array using sequential injection-locking

A coupled push-push oscillator array using a directional coupling circuit is presented. The circuit is composed of unit oscillators and coupling circuits. A push-push oscillator is adopted for the unit oscillator. The output signal is the second harmonic signal (2f₀). The fundamental signal (f₀) is used for the injection signal to achieve the mutual coupling between adjoining unit oscillators. The oscillators are connected by the unilateral coupling circuit which consists of a buffer amplifier and a phase-shifter. Between adjoining oscillators, twice phase shift between adjoining oscillators can be obtained compared to the phase shift made by the coupling circuit in principle. The oscillator array is designed in Ku-band. The phase shift between the adjoining oscillators attains 214 degrees.