EVAL-AD7982SDZ View Datasheet(PDF) - Analog Devices
Part Name
Description
MFG CO.
'EVAL-AD7982SDZ' PDF : 26 Pages View PDF
Data Sheet
TERMINOLOGY
Integral Nonlinearity Error (INL)
INL 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, from the actual voltage producing the midscale
output code, that is, 0 LSB.
Gain Error
The first code transition (from 100 … 00 to 100 … 01) must
occur at a level ½ LSB above nominal negative full scale
(−4.999981 V for the ±5 V range). The last transition (from 011
… 10 to 011 … 11) must occur for an analog voltage 1½ LSB
below the nominal full scale (+4.999943 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.
Spurious-Free Dynamic Range (SFDR)
SFDR is the difference, in decibels, 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 as follows:
ENOB = (SINADdB − 1.76)/6.02
and is expressed in bits.
Noise Free Code Resolution
Noise free code resolution is the number of bits beyond which it is
impossible to distinctly resolve individual codes. It is calculated as
Noise Free Code Resolution = log2(2N/Peak-to-Peak Noise)
AD7982
and is expressed in bits.
Effective Resolution
Effective resolution is calculated as
Effective Resolution = log2(2N/RMS Input Noise)
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 full-scale input signal and is
expressed in decibels.
Dynamic Range
Dynamic range is the ratio of the rms value of the full scale to
the total rms noise measured with the inputs shorted together.
The value for dynamic range is expressed in decibels. It is
measured with a signal at −60 dB so it includes all noise sources
and DNL artifacts.
Signal-to-Noise 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.
Signal-to-Noise-and-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 that are less than
the Nyquist frequency, including harmonics but excluding dc.
The value of SINAD is expressed in decibels.
Aperture Delay
Aperture delay is the measure of the acquisition performance
and is the time between the rising edge of the CNV 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 full-scale step function is applied.
Rev. E | Page 13 of 26
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