a phase detector is provided for detecting the phase difference between a first input signal and a second input signal and providing an output corresponding thereto . the phase detector comprises a dual state phase detector , a tri - state phase detector , a control input for receiving a control signal , and a control circuit for selecting either the dual state phase detector or tri - state phase detector . the dual state phase detector compares the phase difference between the first input signal and the second input signal . the tri - state phase detector compares the phase difference between the second input signal and the inverse of the first input signal . the control circuit selects the output of the dual state phase detector or selects the output of the tri - state phase detector based upon the control signal .