Ultra-low phase-noise VCO for microwave/MM-wave point-to-point backhaul communication

In this paper, an ultra-low phase-noise VCO operating from 2.619 to 2.996 GHz, destined for P2P backhaul communications, is proposed and realized in IBM 0.13-um SiGe process. The VCO uses a differential Colpitts topology with thick-oxide PMOS transistors. 5-bit digitally controlled capacitor array and hyper-abrupt varactors with MIM capacitors are employed for coarse and fine tuning, respectively, which ensure low phase noise across frequency bands. A new stacked-stepped-impedance (SSI) inductor with an enhanced Q factor for low-loss passive components is proposed. The VCO phase noise is thus minimized such that the start-up condition is easy to satisfy with low power consumption. The measured phase noise is a record-low -113.1 dBc/Hz and -135.7 dBc/Hz at 100 kHz and 1 MHz, respectively, from 2.996 GHz carrier. Its FoM of 190.4 dB at 100 kHz offset is the best ever reported. The total power consumption of the VCO is 30 mW.