I am trying to understand how this design is used to measure phase shift between current and voltage of an AC signal. From my understand there should be a PWM signal generated on the output. Resistors R3 and R4 are there to drop the 12 V output of the OP amp to 5 V. Resistor R2 is limiting the current through the diodes D1 and D2. However, I do not understand how the voltage drop on R1 and R5 is phase shifted by the same phase as the current and voltage of the source V1. Can someone please explain that?
simulate this circuit – Schematic created using CircuitLab
UPDATE: Schematic has been corrected.