Apparatus and methods for frequency compensation using two counters

A method for frequency compensation comprising:

• generating a main clock and a sub clock;
• setting a reference period using the main clock;
• sensing a change in the frequency of the sub clock using the reference period;
• and
• providing a compensated frequency based on the changed frequency of the sub clock.

An apparatus for frequency compensation comprising:

• a first clock generator configured to generate a first clock;
• a second clock generator configured to generate a second clock;
• a first counter that is configured to count clock cycles of the first clock and identify a time duration for the first clock to produce a predetermined number of the clock cycles;
• a second counter that is configured to count clock cycles of the second clock during a plurality of time intervals corresponding to the time duration and to determine a change in a frequency of the second clock from the clock cycles of the second clock that are counted during the plurality of time intervals corresponding to the time duration;
• and
• a frequency compensator that is configured to produce a frequency compensation value from the change in the frequency of the second clock.