A 2.3–5-GHz LC-VCO With Source Damping Resistors to Suppress 1/f Noise Up-Conversion

Two RF CMOS voltage-controlled oscillators (VCOs) with source damping resistors to suppress 1/ ${f}$ noise up-conversion are presented in this letter. Two important parameters: the phase deviation from the first harmonic term of the ideal impulse sensitivity function (ISF), and the initial phase of the first harmonic term of channel current, dominate the 1/ ${f}$ noise up-conversion. Based on the outcome, the effects of the source damping resistors on the two phases are analyzed and two VCO prototypes are designed. Implemented in Taiwan Semiconductor Manufacturing Company 180 nm RF CMOS process, the VCOs achieve 64.7% and 50% frequency tuning range at 2.3–4.5 and 3–5 GHz, respectively, and perform phase noise (PN) of −131.03, −129.28, and −124.98 dBc/Hz at 1 MHz offset from output frequencies of 2.33, 3.057, and 4.57 GHz separately.