Phase difference detector with phase inversion of one input signal when phase difference is small

摘要

A phase detector is disclosed in which means are provided for sensing when two AC signals being subjected to phase difference measurement become close in phase, within a predetermined range, and for inverting one of these signals in phase when such a close phase relationship is sensed. The phase difference between the phase inverted signal and the other signal is then measured, and compensation is applied to the measured results such as to compensate for the effects of the phase inversion operation. Insensitivity and "hunting" effects which occur with prior art phase detectors in the region of zero phase difference are thereby eliminated, and an output signal can be obtained which varies in a smooth and continuous manner with variations in the phase difference between the two signals under measurement, over a 360 DEG range.