Hello Brenox,
Are you trying to add noise to a Verilog-AMS model for transient simulations? If so, you can create a noise generator model to inject voltage or current noise in a model. Doing so is quite useful for exploring noise propagation in nonlinear systems such as RF mixers, switched-capacitor filters or delta-sigma A/D converters.
The key is to create a pseudo-random stream of real numbers at a sample rate much higher (about 20x higher) than the maximum frequency of interest. You may then filter that stream as desired, then scale and assign it to a voltage or current.
You may contact me directly for more details or clarification.
Cheers,
Bob Peruzzi
www.RPeruzzi.com