Abstract: The invention provides an improved method and apparatus for detecting the phase difference between a digital data signal and a clock signal. By ensuring that no pulse in the output phase signal is narrow enough to introduce a non-linearity, the present invention avoids a source of non-linearity exhibited in existing phase detectors.In addition, by ensuring that critical timing paths through the circuit contain similar circuit blocks, with similar propagation delays, relative time relationships are preserved from clock and data inputs to XOR inputs. The circuit is therefore largely insensitive to changes in the characteristics of the components so long as they all move together, as they would in an integrated circuit implementation.