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https://designers-guide.org/forum/YaBB.pl Design >> Mixed-Signal Design >> Getting the INL from the DNL of an ADC https://designers-guide.org/forum/YaBB.pl?num=1300415894 Message started by Mischivis on Mar 17th, 2011, 7:38pm |
Title: Getting the INL from the DNL of an ADC Post by Mischivis on Mar 17th, 2011, 7:38pm Can I get the INL if I just know the DNL information of an ADC? For example, if I have a 9 bit ADC and I know the DNL information of the entire code (0.5LSB, 0.8LSB, etc.), can I get the INL from this? |
Title: Re: Getting the INL from the DNL of an ADC Post by boe on Mar 18th, 2011, 3:06am Mischivis, Yes. The 511 DNL values of your 9bit ADC describe the step size between neighbouring codes, so you can determine the characteristic and the INL from it. BOE |
Title: Re: Getting the INL from the DNL of an ADC Post by loose-electron on Mar 18th, 2011, 11:44am I know that this answer is in a dozen textbooks and on the internet as well. Of course you can! the entire static response (Not dynamic) can be derived from the DNL, after all the voltage of each and every LSB step is in the data. |
Title: Re: Getting the INL from the DNL of an ADC Post by carlgrace on Apr 1st, 2011, 9:00am Just add up the different DNL values to get your INL. It is just the running sum (hence the term "integral"). Carl |
Title: Re: Getting the INL from the DNL of an ADC Post by Vladislav D on Apr 16th, 2011, 5:34am I have a doubt. INL is an absolute shift of a transfer from the ideal one. DNL measures the ratio between an ideal and real step. So, if the whole transfer function is shifted, INL will change but DNL remains the same. I don't see correlation between INL and DNL in this case. |
Title: Re: Getting the INL from the DNL of an ADC Post by boe on Apr 18th, 2011, 10:31am Vladislav D wrote on Apr 16th, 2011, 5:34am:
Offset is not a non-linearity, so it should not be part of INL, whatever definition you use. BOE |
Title: Re: Getting the INL from the DNL of an ADC Post by Vladislav D on Apr 18th, 2011, 1:05pm Hi Boe, boe wrote on Apr 18th, 2011, 10:31am:
I don't know about common convention but this is written in the book of ADI about the end point method of measurement INL: "This is the most useful integral linearity measurement for measurement and control applications of data converters (since error budgets depend on deviation from the ideal transfer characteristic, not from some arbitrary "best fit"), and is the one normally adopted by Analog Devices, Inc" Quote:
Offset is not non-linearity. However, offset causes non-linearity as well as second harmonic causes DC offset. Isn't it? |
Title: Re: Getting the INL from the DNL of an ADC Post by boe on May 9th, 2011, 10:48am Vladislav_D, Sorry for the late reply. Vladislav D wrote on Apr 18th, 2011, 1:05pm:
Quote:
B O E |
Title: Re: Getting the INL from the DNL of an ADC Post by carlgrace on May 14th, 2011, 2:53pm This is a situation where the application matters for the definition. A lot of ADCs are used in situations (e.g. imaging, communications) where the absolute deviation from ideal is not important. In those cases best-fit is the way to go. To answer this question definitively, we need to specify the application. Otherwise, we are just chasing our tails. |
Title: Re: Getting the INL from the DNL of an ADC Post by boe on May 17th, 2011, 9:25am Carlgrace, I agree. Vladislav D, I found http://www.analog.com/library/analogdialogue/archives/43-09/EDCh%205%20sampling%20theory.pdf. Do you mean 1st paragraph on p. 5.15 (p. 17 of PDF)? An offset shift will not affect the INL. Cf. Fig. 5.16 on previous page. If you shift transfer characteristics, you also shift dotted line, keeping the linearity error constant. B O E |
Title: Re: Getting the INL from the DNL of an ADC Post by loose-electron on May 18th, 2011, 6:05pm carlgrace wrote on May 14th, 2011, 2:53pm:
Well stated! |
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