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## AD7674 Datasheet(HTML) 11 Page - Analog Devices

 11 / 28 pageAD7674Rev. A | Page 11 of 28DEFINITIONS OF SPECIFICATIONSIntegral Nonlinearity Error (INL)Linearity error refers to the deviation of each individual codefrom a line drawn from negative full scale through positive fullscale. The point used as negative full scale occurs ½ LSB beforethe first code transition. Positive full scale is defined as a level1½ LSB beyond the last code transition. The deviation ismeasured from the middle of each code to the true straight line.Differential Nonlinearity Error (DNL)In an ideal ADC, code transitions are 1 LSB apart. Differentialnonlinearity is the maximum deviation from this ideal value. Itis often specified in terms of resolution for which no missingcodes are guaranteed.Gain ErrorThe first transition (from 000…00 to 000…01) should occur foran analog voltage ½ LSB above the nominal negative full scale(–4.095991 V for the ±4.096 V range). The last transition (from111…10 to 111…11) should occur for an analog voltage1½ LSB below the nominal full scale (4.095977 V for the±4.096 V range). The gain error is the deviation of thedifference between the actual level of the last transition and theactual level of the first transition from the difference betweenthe ideal levels.Zero ErrorThe zero error is the difference between the ideal midscaleinput voltage (0 V) from the actual voltage producing themidscale output code.Spurious-Free Dynamic Range (SFDR)SFDR is the difference, in decibels (dB), between the rmsamplitude of the input signal and the peak spurious signal.Effective Number of Bits (ENOB)ENOB is a measurement of the resolution with a sine waveinput, and is expressed in bits. It is related to S/(N+D) by thefollowing formula:ENOB = (S/[N+D]dB – 1.76)/6.02Total Harmonic Distortion (THD)THD is the ratio of the rms sum of the first five harmoniccomponents to the rms value of a full-scale input signal, and isexpressed in decibels.Dynamic RangeDynamic range is the ratio of the rms value of the full scale tothe rms noise measured with the inputs shorted together. Thevalue for dynamic range is expressed in decibels.Signal-to-Noise Ratio (SNR)SNR is the ratio of the rms value of the actual input signal to therms sum of all other spectral components below the Nyquistfrequency, excluding harmonics and dc. The value for SNR isexpressed in decibels.Signal-to-(Noise + Distortion) Ratio (S/[N+D])S/(N+D) is the ratio of the rms value of the actual input signalto the rms sum of all other spectral components below theNyquist frequency, including harmonics but excluding dc. Thevalue for S/(N+D) is expressed in decibels.Aperture DelayAperture delay is a measure of the acquisition performance andis measured from the falling edge of the CNVST input to whenthe input signal is held for a conversion.Transient ResponseTransient response is the time required for the AD7674 toachieve its rated accuracy after a full-scale step function isapplied to its input.