generation noise in cadence

hi dears,
I am working on a project to compare standard inverter and MRF inverter. MRF inverter is a model of inverter which is so resistive to noise. so, I need to generate external noise to both standard inverter and MRF inverter circuits (in cadence software) to show that the standart inverter output (waveform) will be noisy where as the MRF circuit output is the same as befire (means that resistive to noise).
I designed both circuits without noise, and I could get the correct waveforms. now, my problem is that I dont know how to generate external noise. I did some research and I ve seen that there are three ways to do. first using 'vpwlfile', by generating noise in matlab and open it here. second to use verilog-A. and third is to use vsource.
now, the problem is that I dont know how to do any one of them. can you plz help me and explain to me how to generate noise for example using vpwlf?.
I appreciate your consideration

rgds
Atieh

add a block of MIXER and feed the input from NOISE Gen. block and original Signal Gen. block. .
Now utilize the output with rest of the circuit.

the first one is simple and flexible, i use it in my work. you explain it very clear, any problem then?

hi, thx guys
I decided to use the VPWLF parameter in Cadence, I generated the data from noise using matlab. I copied the floating point data to a notepad text file (1000 points). since my voltage is from zero to 1v. the noise dta ais from -0.5 to 0.5v. and whay I added the VPLWF parameter to each transiter in the standard inverter circuit and I added the location of the notepad file to the VPWL file name. but when I wanted to run my circuit I faced error. it said that error in line one of the text file. then I added the DC voltage, period, and transient time in the parameter properties. then the error changed to "the twidth is not specified or its is incorrect". I played around a bit and I found out its becouse of the period, I am kind of confused now. can u plz tell me what should I exactly do?
I really appreciate ur help.
thx
atieh