[Amps] Re: How IMDs are created

[rfdude at comcast.net]

Bill 
are you then saying that the 3rd order IMD products are no longer: 
2F2-F1 and 2F1-F2. 
2F2 is the second harmonic of F2 and the same with F1. 
So how do you reconcile this?
chris
> At 02:12 AM 1/2/2004 +0000, rfdude at COMCAST.NET wrote:
> 
> >Just to set the record straight: IMD products ARE the mixing terms of the 
> >the "harmonics" with the "fundamental(s) (correct for the lowest order 
IMDs)".
> >
> >For example for a two tone case, F1 and F2, the first close-in-band IMDs 
> >are: 3*F2squared-F1 and 3*F1squared-F2, (F2squared is the 2nd harmonic of 
> >F2, and so on....). Ignoring the amplitude term, this leads to the 3rd 
> >order IMD products: 2F2-F1 and 2F1-F2.
> 
> As long at the non-linear function is continuous and and can be described 
> by a polynomial (Taylor Series).  The mixing of second harmonics and 
> fundamentals does not take place.
> For example, I can have a second order (squared term) which will produce 
> mixing between the two original frequencies and second harmonics of the two 
> frequencies. Even though I have increased the second harmonic content from 
> none to some or a lot it has no effect on the IMD products. Just look at 
> the math. So I say that the production of the IMD products and second 
> harmonics are independent and thus it is no mixing of the second harmonics 
> and fundamentals.
> 
> 73
> Bill wa4lav
>   
>