AD9248BST-65 Analog Devices, Inc., AD9248BST-65 Datasheet - Page 12

• Manufacturer Part Number: AD9248BST-65
• Description: 14-bit, 20/40/65 Msps Dual A/ D Converter
• Manufacturer: Analog Devices, Inc.

AD9248
TERMINOLGY
Aperture Delay
Aperture delay is a measure of the sample-and-hold amplifier
(SHA) performance and is measured from the rising edge of the
clock input to when the input signal is held for conversion.
Aperture Jitter
The variation in aperture delay for successive samples, which is
manifested as noise on the input to the A/D converter.
Integral Nonlinearity (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 1/2 LSB before the first
code transition. Positive full scale is defined as a level 1 1/2
LSB beyond the last code transition. The deviation is measured
from the middle of each particular code to the true straight line.
Differential Nonlinearity (DNL, No Missing Codes)
An ideal ADC exhibits code transitions that are exactly 1 LSB
apart. DNL is the deviation from this ideal value. Guaranteed
no missing codes to 14-bit resolution indicates that all 8192
codes must be present over all operating ranges.
Offset Error
The major carry transition should occur for an analog value 1/2
LSB below VIN+ = VIN- . Offset error is defined as the
deviation of the actual transition from that point.
Gain Error
The first code transition should occur at an analog value 1/2
LSB above negative full scale. The last transition should occur
at an analog value 1 1/2 LSB below the nominal full scale.
Gain error is the deviation of the actual difference between first
and last code transitions and the ideal difference between first
and last code transitions.
Temperature Drift
The temperature drift for zero error and gain error specifies the
maximum change from the initial (25°C) value to the value at
T
Power Supply Rejection
The specification shows the maximum change in full scale
from the value with the supply at the minimum limit to the
value with the supply at its maximum limit.
Total Harmonic Distortion (THD)
The ratio of the rms sum of the first six harmonic components
to the rms value of the measured input signal, expressed as a
percentage or in decibels relative to the peak carrier signal
(dBc).
MIN
or T
MAX
.
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Signal-to-Noise and Distortion (S/N+D, SINAD) Ratio
The ratio of the rms value of the measured 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 relative to the peak carrier
signal (dBc).
Effective Number of Bits (ENOB)
Using the following formula:
device for sine wave inputs at a given input frequency can be
calculated directly from its measured SINAD.
Signal-to-Noise Ratio (SNR)
The ratio of the rms value of the measured input signal to the
rms sum of all other spectral components below the Nyquist
frequency, excluding the first six harmonics and dc. The value
for SNR is expressed in decibels relative to the peak carrier
signal (dBc).
Spurious Free Dynamic Range (SFDR)
The difference in dB between the rms amplitude of the input
signal and the peak spurious signal.
Nyquist Sampling
When the frequency components of the analog input are below
the Nyquist frequency (f
Nyquist sampling.
IF Sampling
Due to the effects of aliasing, an ADC is not necessarily limited
to Nyquist sampling. Higher sampled frequencies will be
aliased down into the first Nyquist zone (DC - f
output of the ADC. Care must be taken that the bandwidth of
the sampled signal does not overlap Nyquist zones and alias
onto itself. Nyquist sampling performance is limited by the
bandwidth of the input SHA and clock jitter (jitter adds more
noise at higher input frequencies).
Two-Tone SFDR
The ratio of the rms value of either input tone to the rms value
of the peak spurious component. The peak spurious component
may or may not be an IMD product.
Out-of-Range Recovery Time
Out-of-range recovery time is the time it takes for the A/D
converter to reacquire the analog input after a transient from
10% above positive full scale to 10% above negative full scale,
or from 10% below negative full scale to 10% below positive
full scale.
ENOB
Preliminary Technical Data
SINAD
1
.
76
CLOCK
6
.
02
/2), this is often referred to as
effective number of bits for a
CLOCK
/2) on the