Hi.
In modeling limiter, we have two options, equivalent-lowpass and baseband models.
If we use equivalent-lowpass model, we can implement AM/AM and AM/PM characteristics easily by table look up, since we consider an envelope only for fundamental output.
But if we use baseband models for limiter, what amplitude should be used in table ?
Limiter outputs include 1st, 2nd, 3rd, ...., etc. harmonics.
I don't think we should use raw amplitude of output in table.
Rather three parameters model for limiter is better.
See page.212-213 of following.
http://btobsearch.barnesandnoble.com/booksearch/isbnInquiry.asp?z=y&btob=Y&isbn=...We can determine three parameter by transient or PSS analysis.
For symmetric limiter
#define Lim3(_v1, s) ( K*(_v1)/pow(pow(K*fabs(_v1)/Limiter_High_Level_V,s)+1.0,1/s) )
Here K, Limiter_High_Level_V and s are parameter to be determined.
I will model limiter like following.
Input signal for limiter is equivalent-lowpass representation.
First AM/PM effect is modeled as equivalent lowpass by table look up.
After AM/PM effect is included, AM/AM effect is modeled by baseband using three parameter model.