PLL / VCO simulation

Can anyone recommend a good tool for simulating the operation of a schematic made up of components such as PLLs, VCOs, mixers, filters.

Thanks

Cadence Spectre,Keysight ADS,NI MWOffice,Ansys Nexxim,

Even Falstad has a simple free PLL simulation.

The keyword for search of such tools is "RF system simulation"

In addition to the tools/frameworks that have been mentioned, there is also Matlab based solution:
http://de.mathworks.com/products/simrf/