Datasheet

DEFINITION OF SPECIFICATIONS
Analog Bandwidth Minimum Conversion Rate
Signal-to-Noise and Distortion (SINAD)
Aperture Delay
Aperture Uncertainty (Jitter)
SINAD + 10Log
10
P
S
P
N
) P
D
Clock Duty Cycle
Signal-to-Noise Ratio (SNR)
Differential Nonlinearity (DNL)
SNR + 10Log
10
P
S
P
N
Effective Number of Bits (ENOB)
Spurious-Free Dynamic Range
ENOB +
SINAD * 1.76
6.02
Two-Tone, Third-Order Intermodulation
Integral Nonlinearity (INL)
Maximum Conversion Rate
ADS5272
www.ti.com ...................................................................................................................................................... SBAS324C – JUNE 2004 – REVISED JANUARY 2009
The analog input frequency at which the spectral This is the minimum sampling rate where the ADC
power of the fundamental frequency (as determined still works.
by FFT analysis) is reduced by 3dB.
SINAD is the ratio of the power of the fundamental
The delay in time between the rising edge of the input (P
S
) to the power of all the other spectral components
sampling clock and the actual time at which the including noise (P
N
) and distortion (P
D
), but not
sampling occurs. including dc.
The sample-to-sample variation in aperture delay.
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
Pulse width high is the minimum amount of time that power of the fundamental is extrapolated to the
the ADCLK pulse should be left in logic ‘ 1 ’ state to full-scale range of the converter.
achieve rated performance. Pulse width low is the
minimum time that the ADCLK pulse should be left in
a low state (logic ‘ 0 ’ ). At a given clock rate, these
SNR is the ratio of the power of the fundamental (P
S
)
specifications define an acceptable clock duty cycle.
to the noise floor power (P
N
), excluding the power at
dc and the first eight harmonics.
An ideal ADC exhibits code transitions that are
exactly 1 LSB apart. DNL is the deviation of any
single LSB transition at the digital output from an
SNR is either given in units of dBc (dB to carrier)
ideal 1 LSB step at the analog input. If a device
when the absolute power of the fundamental is used
claims to have no missing codes, it means that all
as the reference, or dBFS (dB to full-scale) when the
possible codes (for a 12-bit converter, 4096 codes)
power of the fundamental is extrapolated to the
are present over the full operating range.
full-scale range of the converter.
The ENOB is a measure of converter performance as
The ratio of the power of the fundamental to the
compared to the theoretical limit based on
highest other spectral component (either spur or
quantization noise.
harmonic). SFDR is typically given in units of dBc (dB
to carrier).
Distortion
INL is the deviation of the transfer function from a Two-tone IMD3 is the ratio of power of the
reference line measured in fractions of 1 LSB using a fundamental (at frequencies f
1
and f
2
) to the power of
best straight line or best fit determined by a least the worst spectral component of third-order
square curve fit. INL is independent from effects of intermodulation distortion at either frequency 2f
1
– f
2
offset, gain or quantization errors. or 2f
2
– f
1
. IMD3 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 encode rate at which parametric testing is
the full-scale range of the converter.
performed. This is the maximum sampling rate where
certified operation is given.
Copyright © 2004 – 2009, Texas Instruments Incorporated Submit Documentation Feedback 13
Product Folder Link(s): ADS5272