PWM vs. PPL in L298 motor controller
There is no Phase Locked Loop (PLL) on that board, and I can't think of any other "PLL" that could possibly apply. Looking at the schematic, the "PLL" mode that is described in the wiki you linked to is just swapping the enable and direction pins. That's it. 

You can see that this is all that those jumpers do by looking at the example code. Notice how the only difference between the two programs is lines 2-5. The only difference is that the enable and motor pin numbers have different values.