Voltage Controlled Push-Push Oscillator in the Frequency Range of 1200-1400 MHz

In microwave oscillators, the quality factor of the resonators decreases with an increasing frequency. There exist some methods for compensating the losses in the resonators. The push-push configuration is able to improve the oscillator phase noise. In this work, a push-push voltage-controlled oscillator utilizing a parallel coupled resonator has been designed for the frequency range of 1200-1400 MHz. The push-push oscillator consists of two similar Collpits oscillators, which are designed for the frequency range of 600-700 MHz. These sub-oscillators are coupled by a phase coupling network and with 180 degrees phase difference. The in-phase combiner combines the even harmonics of each sub-oscillator and cancels the fundamental and odd harmonics. The overall oscillation of the push-push oscillator consists of the second and even harmonics of the sub oscillators. By this technique, the phase noise is improved 9 dB compared to the case of the stand-alone oscillation of each sub circuit at the output frequency.