ADA4841-X AD [Analog Devices], ADA4841-X Datasheet - Page 10

• Manufacturer Part Number: ADA4841-X
• Manufacturer: AD [Analog Devices]

AD7689
TERMINOLOGY
Least Significant Bit (LSB)
The LSB is the smallest increment that can be represented by a
converter. For an analog-to-digital converter with N bits of
resolution, the LSB expressed in volts is
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 12).
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.
Offset Error
The first transition should occur at a level ½ LSB above analog
ground (38.14μV). The unipolar offset error is the deviation of
the actual transition from that point.
Gain Error
The last transition (from 111…10 to 111…11) should occur for
an analog voltage 1½ LSB below the nominal full-scale. The gain
error is the deviation in LSB (or % of full-scale range) of the
actual level of the last transition from the ideal level after the
offset error is adjusted out. Closely related is the full-scale error
(also in LSB or % of full-scale range), which includes the effects
of the offset error.
Aperture Delay
Aperture delay is the measure of the acquisition performance. It
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.
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.
LSB
(V) =
V
2
REF
N
Rev. PrC | Page 10 of 20
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 + 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 decibels.
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.
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 by the following formula:
and is expressed in bits.
Channel-to-Channel Crosstalk
Channel-to-channel crosstalk is a measure of the level of crosstalk
between any two adjacent channels. It is measured by applying a
DC to the channel under test and applying a full-scale, 100 kHz
sine wave signal to the adjacent channel(s). The crosstalk is the
amount of signal that leaks into the test channel and is
expressed in dB.
Reference Voltage Temperature Coefficient
Reference voltage temperature coefficient is derived from the
typical shift of output voltage at 25°C on a sample of parts at the
maximum and minimum reference output voltage (V
ured at T
where:
V
V
V
T
T
MAX
MIN
REF
REF
REF
ENOB = (SINAD
(Max) = maximum V
(Min) = minimum V
(25°C) = V
= –40°C.
TCV
= +85°C.
MIN
REF
, T(25°C), and T
(
ppm/
REF
°
at 25°C.
) C
Preliminary Technical Data
dB
=
− 1.76)/6.02
V
REF
REF
V
REF
MAX
REF
at T
(
at T
25
. It is expressed in ppm/°C as
(
Max
°
MIN
) C
MIN
, T(25°C), or T
×
– )
, T(25°C), or T
(
T
V
MAX
REF
(
–
Min
T
MIN
)
)
MAX
×
MAX
10
REF
.
.
6
) meas-