Phase detector error compensation apparatus

摘要

An approach to measuring the phase difference between two signals which automatically compensates for errors due to unequal DC offsets between the two channels of phase derived signal circuitry due to aging or temperature variations of components in these circuits by measuring the positive and negative half cycle time periods of the two signals whose phase is being compared as well as measuring the time difference between the same phase point on each of the two signals and combining this information in accordance with an algorithm set forth herein to obtain a phase measurement. The swapping of the signal paths on a periodic basis and averaging of the results is also used to eliminate errors due to signal processing variations in one of the signal paths as compared to the other signal path.