Because of their promise of wide bandwidths and high data-rates, fifth-generation (5G) wireless systems are expected to be deployed worldwide over the next decade. Several bands in the 25-to-40GHz range are allocated for 5G radios. A single widely tunable LC VCO covering the required bands is difficult to design, but is more compact than a set of multiple narrowly tuned VCOs, and is, therefore, preferred. In practice, it is difficult to simultaneously achieve low phase noise and wide tuning range by varying only the capacitor in an LC VCO because (a) switchable capacitor banks have a poor quality factor, Q, at millimeter-wave frequencies and degrade the phase noise, and (b) using wide switches to increase Q increases parasitics and reduces the tuning range.
展开▼
