A Push-Push Oscillator Using Coupled Microstrip Lines in Common Feedback Loop

In this paper, a push-push oscillator using coupled microstrip lines is presented. The usual coupled microstrip lines are formed in the common part of the positive feedback loops. Due to the odd mode transmission in the coupled microstrip line, the phase difference of pi is achieved between the fundamental frequency signals of the two feedback loops. In the experiment, the output power of -2.8 dBm at the second harmonic frequency of 16.0 GHz is obtained. The measured phase noise is -93.0 dBc/Hz at 1 MHz offset frequency. By using the coupled microstrip lines, the push-push oscillation has been achieved successfully.