SpectreRF is a powerful simulator used in Cadence design flow that is time based (that's different respect harmonic balance that is frequency based). It has the usual analysis (dc,ac,transient,noise,sparameter) but also a different kind of analysis (called pss, I don't remember now what it stands for, maybe periodical steady state) that is the starting point for other small signal analysis (pac,pnoise,psp...).
Maybe there is more and more to say, on Cadence site you'll find more details.
Mazz