| Abstract This thesis presents the design of three-, five- and seven-stage voltage-controlled ring oscillators fabricated in 0.18-mum CMOS technology. The ring oscillators operate at 450MHz, 700MHz, 900MHz, 1800MHz, 1900MHz, and 2400MHz, have a narrow operating frequency range and exhibit near-constant amplitude of oscillation versus control voltage. A method for tuning curve linearization is proposed. A novel formula for calculating the frequency of oscillation based on the circuit parameters is derived. The VCO designs consume as low as 474muW from a 1.8V supply, while achieving a figure of merit (FOM) as low as -163.58dB.; This thesis presents a low-power three-stage multi-band voltage-controlled ring oscillator fabricated in a mixed-signal 0.18-mum CMOS technology as well. By using two-input voltage signals, featuring an abrupt and a fine control, six-band (450MHz, 700MHz, 900MHz, 1800MHz, 1900MHz, and 2400MHz) operation was realized in a single VCO. The VCO consumes from 275muW to 647muW from a 1-V supply. The VCO occupies 2461mum2 chip area. |
