I want to analyze the effect of noise on a simple transistor circuit using HSPICE, while maintaining process variation.
The basic setup is as follows:
- The HSPICE models for the transistors are given by the foundry, so I do not want to change anything in the model files (some of them are encrypted as well)
- These model files require a Monte Carlo simulation to incorporate the process variation. I cannot choose the parameters but just performing a Monte Carlo simulation selects the parameters randomly.
- I also want to include additional noise on the output nodes. To perform this, I am utilizing
.TRANNOISEto add transient noise to the nodes.
- The transient noise itself is provided through a Monte Carlo sampling
To include process variation through the model files, I need to use
.TRAN 1ps 10ns SWEEP MONTE=100 SEED=19
To include the transient noise, I need to use
.TRANNOISE V(out) SAMPLES=100 SEED=4
Now my question is this:
How do I combine both of these individual Monte Carlo simulations into one single simulation while maintaining separate control on the seeds?
If I try the following:
.TRAN 1ps 10ns SWEEP MONTE=100 SEED=19 .TRANNOISE V(out) SAMPLES=100 SEED=4
HSPICE throws an error.
I need individual seed control on the Monte Carlo simulation on both the process variation model and on the transient noise. So, it is imperative to have two independent seeds.