Design Of A 5GHz VCO With 0.25um CMOS Technology

Voltage controlled oscillators (VCOs) are an integral part of many electronic systems. They are usually embedded in a phase-locked system. Applications range from clock generation in microprocessors to carrier synthesis in cellular telephones, requiring vastly different oscillator topologies and performance parameters. Robust, high-performance oscillator design in CMOS technology continues to pose interesting challenges. This work presents a fully integrated 5 GHz NMOS-PMOS cross-coupled LC VCO designed for the 0.25um CMOS process. The design is suitable for the usage in a phase-locked loop (PLL). Further researchs are provided for the design of maximum-Q inductors and varactor. The VCO employs patterned silicided ground shield inductors and inversion NMOS-varactors. It features a supply voltage of 2.5V, a core current of only 1.15mA, and a monotone f(V_cont,-characteristic. The frequency is tunable between 4.39 GHz and 5.62 GHz which corresponds to a tuning range of 24.6%. The phase noise which normalized to a 10kHz frequency offset from the carrier is -77.76dBc/Hz. The power-frequency-normalized (PFN) figure of merit is 13.33.