thechopper wrote on Apr 7th, 2008, 7:15pm:Hi,
I think you are just limiting the output dynamic range while improving (or at least keeping) the SNR.
Assuming your cascode does not add any noise, then both the input noise and signal will get amplified by the same number (disregarding frequency domain considerations) so SNR is the same. It is just you can accomodate less signal (and less noise) with the cascoded version.
Hope this helps
Tosei
Hi Tosei. thx for the answer.
Input signal and input noise aren't amplified by the same number in cascoded devices. Because of quadratic relationships, noise progression is of squareroot type. So that at the end, cascoded devices improves SNR.
So my question is: is the output dynamic range improves or not the SNR? I can't prove it, but it seems to me that, in large signal, the more dynamic, you have the better the SNR is.