Hi Rajasekhar,


he didn't actually prove the formula, he simply showed scenarios where it worked. A theory can only be disproven by (counter) example.

That said, I think the formula is much more relavant for companding filters which is the subject of the thesis. The reason is because companding filters have high output signal swings (output of the inner filter) for most of the dynamic range while conventional active filters such as linear active-RC filters only have high output swings when the input signal is large. You have to remember that a conventional active filter will not have high output SNR when the signal is small while a companding filter will have very high gain when the signal is small and thus achieve significant SNR gains.

When I gave you the example using equation A.19 I assumed an output SNR of 10 dB, however, this thesis is talking about an output SNR of 54 dB which is nearly 20000 times higher. A conventional filter cannot achieve 54 dB SNR over a very wide dynamic range (58 dB in this case).

BTW this is really an excellent thesis so thanks so much for showing it to me,


cheers,
Aaron

i feel  dynamic range n SNR are same, provided their is no noise source other than the ckt itself.
SNR takes into account other noises too, apart from the intrinsic noise of MOSFET.

Based on it, i guess DR is always greater than or equal to SNR