Low phase noise push-push VCO using microstrip square open loop multiple split ring resonator and rat race coupler

In this paper, a novel low phase noise push-push voltage-controlled oscillator (VCO) using the microstrip square open loop multiple split ring resonator (SRR) and rat race coupler is presented. The microstrip square open loop multiple SRR has large coupling coefficient value, which makes high quality (Q) factor value, so has reduced the phase noise of VCO. The rat race coupler shows slightly higher transmission compared to Wilkinson combiner and is, therefore, used instead of Wilkinson combiner for improving the performances of VCO. The proposed push-push VCO has the phase noise of -128.33 ~ -126.00 dBc/Hz at 100 kHz in the tuning range of 5.744 ~ 5.864 GHz.