A phase noise improvement of 19 GHz VCO with use of feedback coupled-line resonator

A phase noise improvement of VCO using a novel feedback coupled-line (FBCL) resonator is presented. The Q factor of the FBCL resonator we propose is 2 times higher than that of conventional simple micro-strip line (MSL) resonators, because the FBCL resonator accelerates the phase change vs. frequency with less size increase. A 19 GHz-band push-push VCO with the FBCL resonator exhibited a phase noise level of -104 dBc/Hz at 100 kHz offset, which is 4 dB lower than that of a 10 GHz-band VCO with the MSL resonator. This FBCL topology has a potential to improve the phase noise performance of VCOs by 6 dB.