Harmonics of Cascaded System

[ubabmar]

Hi,


I know that in cascaded system overall gain is the product individual part (system) gain. But i know about the distortions. Like ... What will be the relationship between input and output harmonics?


Please help me........
Regards,
Ubabmar.

 

[steinar96]

I think that if the first stage contains a single nonlinear component (transistor for example) the output of that stage would be harmonics (2f, 3f, 4f) of the input frequency (assuming it's a single frequency f). In that case the input signal to the second stage would contain multiple input frequencies (original frequency + harmonics). Assuming we can expand nonlinear output relations into taylor series containing various terms of the input signal in increasing powers it would mean that the output from the second stage would consist of harmonics made up of harmonics of all the input frequencies into the second stage and sums of harmonics at frequencies consisting of a the sum and difference of all the input frequencies.
These would also be at (2f, 3f, 4f and so on) since the difference between any 2 harmonics is always a integer of the original frequency.
So the total effect i think of a second nonlinear component on harmonics would be to increase the magnitude of the harmonics.

 

[ubabmar]

Hi Steinar96 ,

Thanks for your reply.... What i think is same as yours. But i need some technical document that will give the basic harmonics relationship of harmonic distortion. If you have or found somewhere else please help me....

Regards,
Ubabmar.