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AD7674 Datasheet(PDF) 11 Page  Analog Devices 

AD7674 Datasheet(HTML) 11 Page  Analog Devices 
11 / 28 page AD7674 Rev. A  Page 11 of 28 DEFINITIONS OF SPECIFICATIONS 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. Differential Nonlinearity Error (DNL) In an ideal ADC, code transitions are 1 LSB apart. Differential nonlinearity is the maximum deviation from this ideal value. It is often specified in terms of resolution for which no missing codes are guaranteed. Gain Error The first transition (from 000…00 to 000…01) should occur for an analog voltage ½ LSB above the nominal negative full scale (–4.095991 V for the ±4.096 V range). The last transition (from 111…10 to 111…11) should occur for an analog voltage 1½ LSB below the nominal full scale (4.095977 V for the ±4.096 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. Zero Error The zero error is the difference between the ideal midscale input voltage (0 V) from the actual voltage producing the midscale output code. 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, and is expressed in bits. It is related to S/(N+D) by the following formula: ENOB = (S/[N+D]dB – 1.76)/6.02 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 decibels. Dynamic Range Dynamic range is the ratio of the rms value of the full scale to the rms noise measured with the inputs shorted together. The value for dynamic range is expressed in decibels. 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 decibels. Signalto(Noise + Distortion) Ratio (S/[N+D]) S/(N+D) 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 S/(N+D) is expressed in decibels. Aperture Delay Aperture delay is a measure of the acquisition performance and is measured from the falling edge of the CNVST input to when the input signal is held for a conversion. Transient Response Transient response is the time required for the AD7674 to achieve its rated accuracy after a fullscale step function is applied to its input. 
