PLL(phase detector)

[Oluvision]

Someone told me that I can use the phase detector of a PLL to implement a phase detector. I tried understanding the circuit to this end, but could not figure out to use the phase detector inside the PLL.

 

[crust]

With only the information given, I would guess that the idea was to use the PLL as a d(phi) to voltage converter. A pll could perhaps do this, since in many cases, the operate a VCO. You could perhaps measure the voltage driving the VCO. But my guess would be that you actually need to have the analog loop complete for this to work. I cannot otherwise understand how this might work.

 

[Nigel Goodwin]

A common phase detector in PLL's is simply an XOR gate, the pulse from the output represents the phase difference between the two inputs.