Low Phase Noise Feedback Oscillators Utilizing High-Q SIW Filter with Dielectric Loading

Abstract

Abstract High-Q substrate integrated waveguide (SIW) resonator and its application to low phase noise oscillators are focused in this paper. By drilling air holes in the substrate, SIW bandpass filters (BPFs) with high Q factor could be achieved. This SIW filter is embedded into the feedback loop to be treated as a frequency stabilization element in designing the oscillator. The complex quality factor (Qsc)-peak frequency of the filter is chosen as the final oscillation frequency to obtain low phase noise performance. Moreover, air boxes are utilized instead of the air holes in the substrate to design another oscillator with lower phase noise performance and good harmonic suppression. Two low phase noise oscillators based on fourth-order SIW BPFs with dielectric loading have been studied, demonstrated and fabricated to verify the design concept.