Variable frequency ring oscillator and phase locked loop circuit to which the ring oscillator is adapted

摘要

A ring oscillator having an odd number of inverters selectively connected in a ring-like form includes a changing circuit for changing the ring-like connection by selectively returning the output of an arbitrary odd-numbered one of the inverters as the input to the initial-stage inverter. A phase locked loop circuit having this ring oscillator is also formed using this technique.