A wideband push-push VCO jusing a phase shifter in the common feedback loop

In this paper, a very wideband push-push VCO using a phase shifter with varactor diodes is presented. In the circuit, the phase shifter is arranged in the common part of the positive feedback loops that determine the oscillating frequency. The circuit structure is very simple and compact due to the double-sided MIC structure. This type of push-push oscillator is suitable for a wideband VCO compared with a negative resistance type one. In the experiment, the developed push-push VCO in Ku-band achieves wide tuning frequency range of 1.85 GHz (relative bandwidth =11.6 %). The phase noise is -97.7 to -103.3 dBc/Hz at the offset frequency of 1 MHz.