Modelling the frequency response of active loop filter whing PLL architecture using ADS.
The spice model that is on the OP27 product page can still be imported into ADS. It must be noted, though, that we have not tested this on Keysight ADS. We do our best to model them with various simulators in mind, so I would think this should still work, though I cannot make any guarantees.
Also, I would like to mention that you also might want to take a look at the ADA4625. On page 22 of the datasheet, there is a good discussion of using the ADA4625 as an active loop filter for PLLs. It is especially suitable for these types of applications. There is a SPICE model available for this product as well.