Digitally controlled oscillator using active inductor based on CMOS inverters

A digitally controlled oscillator (DCO) suitable for multi-standards radio-frequency (RF) operation is presented. It has an LC topology using an active inductor based on CMOS controllable inverters. The tunability of the oscillator frequency is ensured by varying the digital word applied to the inverters´ control voltages. The proposed DCO has a small area and exhibits a high-frequency tuning range while achieving low power consumption with good stability against process variations.