Frequency detector

A method comprising:

• generating first and second signals such that a frequency of the first signal is the same as a frequency of the second signal and such that the second signal is phase-shifted by a fixed amount with respect to the first signal;
• generating a third signal having a frequency that corresponds to an absolute value of a difference between the frequency of the first signal and an integer multiple of a frequency of the reference signal;
• generating a fourth signal having a frequency that corresponds to an absolute value of a difference between the frequency of the second signal and an integer multiple of the frequency of the reference signal;
• and
• generating a fifth signal indicative of whether a phase relationship between the third and fourth signals is a leading phase relationship, a lagging phase relationship, or an in-phase relationship.

A device comprising circuitry configured to:

• generate first and second signals such that a frequency of the first signal is the same as a frequency of the second signal and such that the second signal is phase-shifted by a fixed amount with respect to the first signal;
• generate a third signal having a frequency that corresponds to an absolute value of a difference between the frequency of the first signal and an integer multiple of a frequency of the reference signal;
• generate a fourth signal having a frequency that corresponds to an absolute value of a difference between the frequency of the second signal and an integer multiple of the frequency of the reference signal;
• and
• generate a fifth signal indicative of whether a phase relationship between the third and fourth signals is a leading phase relationship, a lagging phase relationship, or an in-phase relationship.