LAUSR

In this brief, an X-band low phase noise oscillator based on the substrate integrated waveguide (SIW) filtering rat-race coupler (FRRC) is proposed. The FRRC in the oscillator design is utilized to act as the frequency-stabilized component, power splitter and matching network simultaneously. It exhibits the merits of high quality factor, high circuit integration and decent impedance matching. For verification, the proposed prototype exploiting an improved SIW FRRC has been investigated, fabricated and measured. It demonstrates that the parallel-feedback oscillator works at 11.03 GHz. The rejection of second and third harmonic signals is up to 49.6 dBc and 48.8 dBc, respectively. In addition, the oscillator exhibits a low phase noise performance of −142.9 dBc/Hz at 1-MHz frequency offset from the oscillation frequency.