Actually the 3LSB offset will reduce ENOB. The reason is that ENOB is based on how well an ADC digitizes a full scale sine wave. The 3LSB offset error will distort the wave for low values, returning zero when the voltage is not zero.
That's why ENOB is so useful. Almost any fault in an ADC will lower ENOB.
So I will stick with people like Walter Kester for information on ADCs, not your guesses.
That is why I suggested that, since you seem to have got a very clean signal, a suitable cyclic perturbation signal would be better than arbitrary, uncharacterised noise.You don't listen. I said I don't do oversampling, I get a better converter. I never suggested a way to inject noise for oversampling. I just said oversampling won't work because the noise levels are so low.
I played with resistors and pickup by longer wires between the source and ADC to see how sensitive it was.
Adding a cyclic perturbation signal seems like a really bad idea. You should just spend $5 for a better ADC.
This is so basic, I don't see why I am having to lay this out for a third time.I ignore you because what you are saying is at odds with recognized authorities.
You don't even know what the definition of resolution is for a ADC. Show me a link to a definition where the it's other than the number of bits output by the converter.
I have spent my career at the finest science labs in the world. Some of the world's best analog and mixed signal engineers are in these labs. As a scientist I depended on them and learned from them.
Who are you? What is the basis of your authority? You never answered whether you are really an EE.