Various systems and methods for clock generation are disclosed herein. As just one example, a system for clock generation is disclosed that includes a phase/frequency control circuit that provides a feedback control; a multi-range selector circuit that receives the feedback control; and a controlled oscillator that provides an output with a phase and frequency at least in part governed by the multi-range selector circuit and the feedback control. In various instances of the aforementioned embodiments, the controlled oscillator is a ring oscillator relying on inherent capacitance.