An X-Band Low Phase Noise Oscillator with High Harmonic Suppression Using SIW Quarter-Wavelength Resonator

This paper presents a low phase noise oscillator with high harmonic suppression employing a pair of substrate integrated waveguide (SIW) quarter-wavelength resonators (QWR) in the feedback loop of the oscillator. By tuning the width of the SIW-QWR based filter, the stopband bandwidth can be extended while maintaining the high group delay in the passband. Taking advantages of the proposed SIW-QWR, an X-band low phase noise oscillator with the second and third harmonic suppression is designed, fabricated and tested. The measured results show that the oscillator operates at 8.08 GHz with -2.14 dBm output power. The second and third harmonic suppression of the presented oscillator can reach to 39.23 dB and 67.64 dB, respectively, with a single SIW-QWR filter. The phase noise performance of the proposed oscillator are -109.94 dBc/Hz at 100 kHz frequency offset and -130.36 dBc/Hz at 1 MHz frequency offset, respectively.