A high-performance CMOS multiphase voltage-controlled oscillator for communication systems

A multiphase oscillator employing phase-setting and oscillation-generation units was developed for modern communication systems. The phase-setting unit includes multiple cascading phase-shifting cells the number of which determines output signal phase differences. The oscillation-generation unit consists of multiple oscillators to trigger the phase-setting unit. This configuration ensures that the proposed multiphase oscillator has good oscillation quality and high phase accuracy. In addition, a voltage-controlled ring oscillator capable of generating two oscillation signals with a phase difference of 180° is designed. It not only decreases the settling time of the multiphase oscillation system, but also reduces power dissipation due to its simplicity. By using TSMC 1P6M 0.18 μm CMOS technology, the proposed multiphase voltage-controlled oscillator (VCO) yields oscillation signals ranging from 2.37 GHz to 2.53 GHz at a supply voltage of 1.8 V. There are 8 oscillation signals with phase differences of 45°, 90°, 135°, 180°, 225°, 270°, 315° and 360°. Power dissipation is around 4.21 mW to 4.88 mW.