aaron_do
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Hi all,
my question is about intermodulation (IM). Assume you have an output,
y(t) = a0 + a1x(t) + a2 x^2(t) + a3 x^3(t) +...
The IM3 component arises due to a3x^3(t). Suppose you are concerned with the IM3 product arising from x1 x2 and x3 which have frequencies f1, f2, and f3 respectively. Then the output IM3 component will be
IM3 = a3*x1(t)*x2(t)*x3(t)
suppose you want the IM3 product at f1+f2+f3. a3 can be a function of frequency. Therefore, my question is, to calculate IM3, at what frequency do we calculate a3? Is it at f1+f2+f3 or is it something else, for example, cube root of a3 at f1 * a3 at f2 * a3 at f3?
Lastly, when we simulate IIP3, we run a PSS analysis and a PAC analysis, where the PSS analysis is only run at one frequency. So therefore, i seems that the simulator does not calculate a3(f). So is it true to say that the IM3 calculated by spectre is less accurate as the PAC frequency becomes further away from the PSS frequency?
thanks, Aaron
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