A circuit[20] for generating a signal that is proportional to the phase difference between a reference signal and a variable frequency signal. The circuit[20] includes a reference generating circuit[21] for generating N phase shifted reference signals from the reference signal. Each of the phase shifted reference signals has the same frequency and a different phase. The phase of the n th one of the phase shifted reference signals is equal to 360n/N degrees, where N>1 and n runs from 0 to N-1. A phase detection circuit[22] generates a phase output signal proportional to the phase difference between the variable frequency signal and the phase shifted reference signal currently being outputted by the reference generating circuit. The phase output signal has value of I when the output signal corresponds to a phase difference of 360/N degrees. An overflow detection circuit[24] determines when the phase output signal has an absolute value greater than I and generates a count signal and a phase adjustment signal when this situation is detected. The phase adjustment signal is coupled to the reference generating circuit[21] and causes the reference generating circuit[21] to select a new phase shifted reference signal. A counter[25] is then incremented/decremented to track the accumulated phase adjustments. A digital to analog converter[26] converts the digital value in the counter[25] to a signal having an amplitude equal to MI, where M is the digital value. A sum circuit[27] adds this signal to the phase output signal.