Abstract: A differential ring oscillator includes a plurality of delay stages connected in a ring. At least one of the delay stages includes: a current source, arranged to generate a bias current according to a coarse tuning signal; a latching circuit arranged to generate a differential output signal to a next delay stage according to a differential input signal from a previous delay stage; a capacitive array arranged to provide a first capacitance according to a fine tuning signal; and a varactor device arranged to provide a second capacitance according to a controllable signal for locking an oscillating frequency of the differential ring oscillator to a target frequency. The coarse tuning signal and fine tuning signal are arranged for adjusting the oscillating frequency of the differential ring oscillator to, respectively, reach a predetermined frequency range including the target frequency and to approach the target frequency in the predetermined frequency range.

Abstract: A differential ring oscillator includes a plurality of delay stages connected in a ring. At least one of the delay stages includes: a current source, arranged to generate a bias current according to a coarse tuning signal; a latching circuit arranged to generate a differential output signal to a next delay stage according to a differential input signal from a previous delay stage; a capacitive array arranged to provide a first capacitance according to a fine tuning signal; and a varactor device arranged to provide a second capacitance according to a controllable signal for locking an oscillating frequency of the differential ring oscillator to a target frequency. The coarse tuning signal and fine tuning signal are arranged for adjusting the oscillating frequency of the differential ring oscillator to, respectively, reach a predetermined frequency range including the target frequency and to approach the target frequency in the predetermined frequency range.