An X-Band Low Phase Noise Parallel-Feedback Oscillator Based on SIW Dual-Mode Filtering Power Divider

In this brief, a new low phase noise feedback oscillator based on substrate integrated waveguide (SIW) dual-mode filtering power divider (DMFPD) is proposed. Several via perturbations are added to the cavity to make the TM010 and TM110 modes form a two order DMFPD. In the oscillator design, the DMFPD can achieve both frequency stabilization and power distribution by using only one single circular cavity. Therefore, high circuit integration and low insertion loss can be realized. Meanwhile, the controllable transmission zero near the upper passband edge can increase the group delay peak to improve the phase noise performance. For verification, the proposed oscillator has been investigated, fabricated and measured. The measured result shows that the parallel-feedback oscillator works at 9.97 GHz and the phase noise is -139.6 dBc/Hz at 1-MHz frequency offset from the oscillation frequency.