Low phase noise VCO using microstrip square open loop multiple split ring resonator

In this paper, a novel voltage-controlled oscillator (VCO) using the microstrip square open loop multiple split ring resonator (OLMSRR) is presented for reducing the phase noise. The square-shaped multiple split ring resonator (MSRR) having the form of the microstrip square open loop is investigated to realize this purpose. Compared with the conventional microstrip line resonator and the microstrip square open loop resonator, the microstrip square OLMSRR has the larger coupling coefficient value, which makes a higher Q value, and has reduced the phase noise of VCO. The proposed VCO has the phase noise of −124.5 ∼ −122.0 dBc/Hz @ 100 kHz in the tuning range, 5.746 ∼ 5.84 GHz. The figure-of-merit (FOM) of this VCO is −203.96 ∼ −201.6 dBc/Hz @ 100 kHz in the same tuning range. Compared with VCOs using the conventional microstrip line resonator and the microstrip square open loop resonator, the phase noise property of VCO using the proposed resonator has been improved in 25.66 dB and 8.34 dB, respectively.