FREQUENCY CONTROL METHOD AND CIRCUIT FOR RING OSCILLATOR

摘要

Provided are a frequency control method and circuit for a ring oscillator. The method comprises the following steps: obtaining, by means of a current bias circuit, a current having a positive temperature coefficient; using the current having the positive temperature coefficient to obtain a voltage having a positive temperature coefficient that is in set proportion to the current having the positive temperature coefficient; and applying the voltage having the positive temperature coefficient to a ring oscillator to obtain a stable output frequency. The method prevents the output frequency of the ring oscillator from being affected by temperature, and greatly improves stability of the output frequency. The method prevents an external power source from affecting the output frequency of the ring oscillator, and provides a good power supply rejection ratio. When each component of the current bias circuit, a voltage generation circuit and the ring oscillator is manufactured by the same process, the change of a threshold voltage of each component with temperature is identical, and the influence of the manufacturing process to the output frequency of the ring oscillator can be compensated.