New wideband∕dualband CMOS LC voltage-controlled oscillator

Abstract

A wideband voltage-controlled oscillator (VCO) with a frequency range from 830 MHz to 2.4 GHz is presented. The VCO has two control inputs, one for continuous control of the output frequency and one for band switching, and two quadrature outputs. Based on a 0.25 /spl mu/m CMOS process, this VCO is simulated for the supply voltage of 2 V. A wide tuning range of 98% is obtained in two independent bands. The harmonic distortions are kept low enough within the entire frequency range. The phase noise is -105 dBc/Hz at 400 kHz offset for the oscillation frequency of 830 MHz, and -89 dBc/Hz at 400 kHz offset for the oscillation frequency of 2.42 GHz. The VCO has a gain of 745.6 MHz/V for its first band and 1.22 GHz/V for its second band. Accurate quadrature outputs are maintained throughout the entire frequency range, as needed in all modern transceiver architectures. Its 2nd harmonic is also reduced by a compensation circuit to less than -33 dB in the worst case at the frequency of 2.42 GHz