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AD7982 Datasheet(PDF) 8 Page  Analog Devices 

AD7982 Datasheet(HTML) 8 Page  Analog Devices 
8 / 16 page AD7684 Rev. A  Page 8 of 16 TERMINOLOGY Integral Nonlinearity Error (INL) Linearity error refers to the deviation of each individual code from a line drawn from negative full scale through positive full scale. The point used as negative full scale occurs ½ LSB before the first code transition. Positive full scale is defined as a level 1½ LSB beyond the last code transition. The deviation is measured from the middle of each code to the true straight line (see Figure 21). Differential Nonlinearity Error (DNL) In an ideal ADC, code transitions are 1 LSB apart. DNL is the maximum deviation from this ideal value. It is often specified in terms of resolution for which no missing codes are guaranteed. Zero Error Zero error is the difference between the ideal midscale voltage, that is, 0 V, and the actual voltage producing the midscale output code, that is, 0 LSB. Gain Error The first transition (from 100 . . . 00 to 100 . . . 01) should occur at a level ½ LSB above the nominal negative full scale (−4.999924 V for the ±5 V range). The last transition (from 011…10 to 011…11) should occur for an analog voltage 1½ LSB below the nominal full scale (4.999771 V for the ±5 V range). The gain error is the deviation of the difference between the actual level of the last transition and the actual level of the first transition from the difference between the ideal levels. SpuriousFree Dynamic Range (SFDR) SFDR is the difference, in decibels (dB), between the rms amplitude of the input signal and the peak spurious signal. Effective Number of Bits (ENOB) ENOB is a measurement of the resolution with a sine wave input. It is related to SINAD by the following formula ENOB = (SINADdB − 1.76)/6.02 and is expressed in bits. Total Harmonic Distortion (THD) THD is the ratio of the rms sum of the first five harmonic components to the rms value of a fullscale input signal and is expressed in dB. SignaltoNoise Ratio (SNR) SNR is the ratio of the rms value of the actual input signal to the rms sum of all other spectral components below the Nyquist frequency, excluding harmonics and dc. The value for SNR is expressed in dB. Signalto(Noise + Distortion) Ratio (SINAD) SINAD is the ratio of the rms value of the actual input signal to the rms sum of all other spectral components below the Nyquist frequency, including harmonics but excluding dc. The value for SINAD is expressed in dB. Aperture Delay Aperture delay is a measure of the acquisition performance and is the time between the falling edge of the CS input and when the input signal is held for a conversion. Transient Response Transient response is the time required for the ADC to accurately acquire its input after a fullscale step function is applied. 
