Design of low phase noise VCO using microstrip complimentary split ring resonator

The low phase noise voltage-controlled oscillator (VCO) using the microstrip complimentary split ring resonator (CSRR) is presented. The designed resonator of VCO is an array of CSRRs etched on the center signal line of the microstrip. The CSRR has a large coupling coefficient value, which makes a narrow band above the resonant frequency, and has reduced the phase noise of the VCO. This VCO has presented the phase noise of -120.84 ~ -118.54 dBc/Hz @ 100 kHz in the tuning range, 5.713 ~ 5.811 GHz. The figure-of-merit (FOM) of the VCO is -199.52 ~ -197.33 dBc/Hz @ 100 kHz in the same tuning range. The phase noise of the VCO using the CSRR has been reduced -19 dB compared with that of the conventional VCO using line resonator.