I've had good luck with a phase detector based on the AD9901. It produces digital outputs
that I can difference and filter to yield a voltage that indicates phase difference of the incoming signals.
However, I really like the features available on chips like the ADF4002 and the ADF4106. The problem is that
these parts have bloody charge pumps on their outputs.
I've tried several hacks to generate a nice, linear phase error signal from these devices, but my results are
What is the proper method to produce a phase error signal from a charge-pump based device?