This paper presents a two-stage CMOS differential voltage-controlled ring oscillator (VCO). The VCO is intended to operate as a frequency synthesizer in a PLL to generate local oscillator frequency (LO) for an acquisition system, providing quadrature output. The proposal is to design a differential VCO that has a wide operating frequency tuning range with low power consumption, better phase-noise performance and good linearity between the frequency and control voltage. Simulation results verify the theoretical development and address the layout design. The circuit was designed and simulated in 0.18µm IBM CMOS technology.
Luciano Severino de Paula, Eric E. Fabris, Sergio