Wideband Varactorless $LC$ VCO Using a Tunable Negative-Inductance Cell

A wideband LC voltage-controlled oscillator (VCO) design with a new varactorless frequency-tuning technique is presented. The wideband continuous frequency tuning is achieved using a tunable negative-inductance cell. Fabricated in a 0.35-μm SiGe BiCMOS process, the varactorless VCO achieves a continuous tuning range of 24.5%. An overall tuning range of 31% from 3.8 to 5.2 GHz is achieved when the continuous tuning is combined with a 2-bit switched capacitor array. The measured phase noise is - 109.8 and - 109.5 dBc/Hz at 1-MHz offset from a 3.8- and a 5.2-GHz carrier frequency. The proposed VCO has demonstrated performance that is better than other wideband varactorless VCOs in the literature.