A novel dual-source-feedforward ring oscillator with enhanced swing and low phase noise

In this paper, a novel feedforward ring oscillator is presented. The proposed oscillator adopts a dual-source-feedforward structure, which connects the output of the auxiliary path to the two sources of the main path inverter, improves the symmetry and voltage swing of the oscillation signal, and significantly reduces the contribution of flicker noise to the overall phase noise. The working process and the rationale behind the phase noise optimization of the novel structure are further analyzed. Compared with the conventional feedforward ring oscillator, using the same design parameters, the proposed oscillator can reduce the phase noise at 1MHz by at least 12dBc while simultaneously gaining a better figure of merit (FoM) of 168dBc/Hz.