The proliferation of multiple communication standards and the constant data-rate enhancement set feed-forward ring oscillators (FFRO) as prominent clock generation circuits due to their wide operating frequency range. However, signal-to-noise ratio (SNR) and phase noise masks appear as major concerns when clock sources intend large tuning ranges. In this work, we developed a phase noise model based on a multi-loop control system theory applied to FFROs. Besides showing a good match between the proposed model and Spice simulations, the model give qualitative insights to adjust the extended frequency range with awareness of the phase noise performance. For instance, we show that it is possible to achieve a 6dB phase noise performance improvement for a given feed-forward strength.