Design of VCO with a Differential Tunable Active Inductor

This paper presents a wide tuning rang CMOS voltage control oscillator (VCO) suitable for radio frequency operation. The oscillator based upon the classic LC-tuned negative-resistance topology, with a novel low voltage, high performance active inductor. In the proposed circuits' structure, the coarse frequency tuning is provided by the tunable active inductor, while the fine tuning is controlled by varactor. Using a 0.18μm CMOS process, complete pattern VCOs are designed in ADS. The output frequency is 5.5GHz. The measured phase noise in 1-MHz offset is -81dBc. The non existence of passive components causes VCO to have the smaller chip area than the circuit with passive inductors.