Datasheet

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DEFINITION OF SPECIFICATIONS
SNR + 10Log
10
P
S
P
N
(1)
SINAD + 10Log
10
P
S
P
N
) P
D
(2)
ENOB +
SINAD * 1.76
6.02
(3)
Production Data
ADS5541
SBAS307C – MAY 2004 – REVISED FEBRUARY 2007
Offset Error
Analog Bandwidth
The offset error is the difference, given in number of
The analog input frequency at which the power of the
LSBs, between the ADC actual average idle channel
fundamental is reduced by 3dB with respect to the
output code and the ideal average idle channel
low frequency value.
output code. This quantity is often mapped into mV.
Aperture Delay
Temperature Drift
The delay in time between the falling edge of the
The temperature drift coefficient (with respect to gain
input sampling clock and the actual time at which the
error and offset error) specifies the change per
sampling occurs.
degree Celsius of the parameter from T
MIN
to T
MAX
. It
is calculated by dividing the maximum deviation of
Aperture Uncertainty (Jitter)
the parameter across the T
MIN
to T
MAX
range by the
The sample-to-sample variation in aperture delay.
difference (T
MAX
– T
MIN
).
Clock Pulse Width/Duty Cycle
Signal-to-Noise Ratio (SNR)
The duty cycle of a clock signal is the ratio of the
SNR is the ratio of the power of the fundamental (P
S
)
time the clock signal remains at a logic high (clock
to the noise floor power (P
N
), excluding the power at
pulse width) to the period of the clock signal. Duty
dc and the first eight harmonics.
cycle is typically expressed as a percentage. A
perfect differential sine wave clock results in a 50%
duty cycle.
Maximum Conversion Rate
SNR is either given in units of dBc (dB to carrier)
when the absolute power of the fundamental is used
The maximum sampling rate at which certified
as the reference or dBFS (dB to Full-Scale) when the
operation is given. All parametric testing is performed
power of the fundamental is extrapolated to the
at this sampling rate unless otherwise noted.
converter full-scale range.
Minimum Conversion Rate
Signal-to-Noise and Distortion (SINAD)
The minimum sampling rate at which the ADC
SINAD is the ratio of the power of the fundamental
functions.
(P
S
) to the power of all the other spectral
components including noise (P
N
) and distortion (P
D
),
Differential Nonlinearity (DNL)
but excluding dc.
An ideal ADC exhibits code transitions at analog
input values spaced exactly 1LSB apart. The DNL is
the deviation of any single step from this ideal value,
measured in units of LSBs.
SINAD is either given in units of dBc (dB to carrier)
Integral Nonlinearity (INL)
when the absolute power of the fundamental is used
as the reference or dBFS (dB to full-scale) when the
The INL is the deviation of the ADC transfer function
power of the fundamental is extrapolated to the
from a best fit line determined by a least squares
converter full-scale range.
curve fit of that transfer function, measured in units
of LSBs.
Effective Number of Bits (ENOB)
Gain Error
The ENOB is a measure of a converter's
performance as compared to the theoretical limit
The gain error is the deviation of the ADC actual
based on quantization noise.
input full-scale range from its ideal value. The gain
error is given as a percentage of the ideal input
full-scale range. Gain error does not account for
variations in the internal reference voltages (see the
Electrical Characteristics section for limits on the
variation of V
REFP
and V
REFM
).
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