ADS5560 Datasheet, PDF (51/61 Pages) Texas Instruments – 16-BIT, 40/80 MSPS ADCs WITH DDR LVDS/CMOS OUTPUTS

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11 Device and Documentation Support
ADS5560, ADS5562
SLWS207B – MAY 2008 – REVISED JANUARY 2016
11.1 Device Support
11.1.1 Device Nomenclature
Analog Bandwidth The analog input frequency at which the power of the fundamental is reduced by 3 dB with
respect to the low -frequency value.
Aperture Delay The delay in time between the rising edge of the input sampling clock and the actual time at
which the sampling occurs.
Aperture Jitter The sample-to-sample variation in aperture delay.
Clock Pulse Width/Duty Cycle The duty cycle of a clock signal is the ratio of the time the clock signal remains
at a logic high (clock pulse width) to the period of the clock signal. Duty cycle is typically expressed
as a percentage. A perfect differential sine-wave clock results in a 50% duty cycle.
Differential Nonlinearity (DNL) An ideal ADC exhibits code transitions at analog input values spaced exactly 1
LSB apart. The DNL is the deviation of any single step from this ideal value, measured in units of
LSBs
Effective Number of Bits (ENOB) The ENOB is a measure of a converter’s performance as compared to the
theoretical limit based on quantization noise.
ENOB
=
SINAD - 1.76
6.02
(8)
Gain Error The gain error is the deviation of the ADC’s actual input full-scale range from its ideal value. The
gain error is given as a percentage of the ideal input full-scale range.
Integral Nonlinearity (INL) The INL is the deviation of the ADC’s transfer function from a best fit line determined
by a least squares curve fit of that transfer function, measured in units of LSBs.
Maximum Sample Rate The maximum conversion rate at which certified operation is given. All parametric
testing is performed at this sampling rate unless otherwise noted.
Minimum Sample Rate The minimum conversion rate at which the ADC functions.
Offset Error The offset error is the difference, given in number of LSBs, between the ADC’s actual average idle
channel output code and the ideal average idle channel output code. This quantity is often mapped
into mV.
Signal-to-Noise and Distortion (SINAD) SINAD is the ratio of the power of the fundamental (P_S) to the power
of all the other spectral components including noise (P_N) and distortion (P_D), but excluding DC.
SINAD is either given in units of dBc (dB to carrier) when the absolute power of the fundamental is used
as the reference, or dBFS (dB to full scale) when the power of the fundamental is extrapolated to the full-
scale range of the converter.
SINAD = 10Log^{10 Ps}
P_N + P_D
(9)
Signal-to-Noise Ratio SNR is the ratio of the power of the fundamental (P_S) to the noise floor power (P_N),
excluding the power at DC and the first nine harmonics.
SNR is either given in units of dBc (dB to carrier) when the absolute power of the fundamental is used as
the reference, or dBFS (dB to full scale) when the power of the fundamental is extrapolated to the full-
scale range of the converter.
SNR
=
10Log¹⁰
P_s
P_N
(10)
Spurious-Free Dynamic Range (SFDR) The ratio of the power of the fundamental to the highest other spectral
component (either spur or harmonic). SFDR is typically given in units of dBc (dB to carrier).
Temperature Drift The temperature drift coefficient (with respect to gain error and offset error) specifies the
change per degree Celsius of the parameter from T_MIN to T_MAX. It is calculated by dividing the
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