It is a tutorial to demo spectreRF simulation for mixer design.
From its Conclusion:
This tutorial illustrates how to use Spectre to s imulate a mixer and to extract design
parameters such as IP3, 1dB compression point, or port-to-port isolation. Various
techniques using PSS, Pnoise, PAC, and QPSS analyses are demonstrated. Spectre
Harmonic Balance and Time domain algorithms are demonstrated and their accuracies